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WARNING:
This guide automatically assumes that you have all DLC installed.
This guide is not spoiler-proofed. If you wish for your Isaac experience not to be spoiled, turn back now.

• regular rocks,
  
• tinted rocks,
  
• super secret rocks (tinted rock 2.0),
  
• rigged rocks,
  
• spiked rocks,
  
• pots,
  
• buckets,
  
• mushrooms,
  
• skulls,
  
• marked skulls,
  
• polyps

NOTE: All of the rocks below block the player and their tears. This can be bypassed by having flight and spectral tears respectively. All of the rocks below can be destroyed by explosions, and can fill gaps unless specified otherwise (Navigate to 'Environment - Gaps' to learn about filling gaps). These notes have been added to avoid needless clutter.

• normal fires,
  
• red fires,
  
• blue fires,
  
• purple fires,
  
• white fires

NOTE: All of the fires below block the player and their tears. Tears can pass through campfires if they're piercing or spectral. This note has been added to avoid needless clutter.

• poop,
  
• corny poop,
  
• red poop,
  
• golden poop,
  
• rainbow poop,
  
• black poop (meconium),
  
• white poop,
  
• giant poop,
  
• charming poop

NOTE: All of the poops below block the player and their tears. This can be remedied by flight and spectral tears respectively. All poops can fill gaps unless specified otherwise. All poops can be destroyed by tears and explosions unless specified otherwise. This note has been added to avoid needless clutter.

• red creep,
  
• green creep,
  
• yellow creep,
  
• black creep,
  
• white creep,
  
• blue creep,
  
• grey creep,
  
• orange creep,
  
• brown creep,
  
• static creep

• room clears,
• boss drops,
• machines,
• beggars,
• buying them in Shops,
• as a pre-defined spawn in certain room layouts,
• as an effect of various active/passive items

NOTE: "2 of X" cards will give you 2 instances of the pickup, should your pickup count be 0

Stat Change Effects

Name

Effect

Horse Pill Effect

Bad Trip

The player takes a full heart of damage

The player takes two hearts of damage

Balls of Steel

The player gains two soul hearts

The player gains four soul hearts

Bombs Are Key

The bomb and key counts are swapped, including golden bombs and keys

Bomb/key counts increase by 50% when swapped

Full Health

Heals all of the player's empty red heart containers

Adds 3 soul hearts alongside the base effect

Health Down

Removes one red heart container

Removes two heart containers

Health Up

Adds a red heart container

Adds two red heart containers

Range Down

-0.60 range

-1.20 range

Range Up

+0.75 range

+1.50 range

Speed Down

-0.12 speed

-0.24 speed

Speed Up

+0.15 speed

+0.30 speed

Tears Down

-0.28 tears

-0.56 tears

Tears Up

+0.35 tears

+0.70 tears

Luck Down

-1.00 luck

-2.00 luck

Luck Up

+1.00 luck

+2.00 luck

Shot Speed Down

-0.15 shot speed

-0.30 shot speed

Shot Speed Up

+0.15 shot speed

+0.30 shot speed

Experimental Pill

Decreases one of the player's stats and increases another

The stat changes are doubled.

Positive Miscellaneous Effects

Name

Effect

Horse Pill Effect

Bad Gas

The player farts, poisoning nearby enemies

The poison covers the entire room

Pretty Fly

Spawns a permanent fly orbital, which blocks shots

Spawns a permanent Big Fan orbital

48h Energy

Fully recharges your active item and spawns 1-2 batteries

Spawns more batteries alongside the base effect

I Can See Forever!

Grants an effect for the current floor, which opens all secret rooms

Reveals the map alongside the base effect

Lemon Party

Spawns a large puddle of yellow creep

The puddle roughly doubles in size, covering an entire normal room

Percs!

Turns all damage sources into half-heart damage sources for the duration of the room, identically to the Wafer item

-

One makes you smaller

The player and their hitbox decrease in size

The player's and their hitbox's sizes decrease twice

Infested!

Destroys all poop in the room and spawns an equal amount of friendly spiders

Twice as many spiders spawn

Infested?

Spawns an amount of friendly spiders equal to the amount of enemies in the room.
Spawns 1-3 spiders in rooms with no enemies

Twice as many spiders spawn

Power Pill!

Grants the Gamekid item effect

Grants the Huge Growth card effect alongside the base effect

Friends till the End!

Spawns 3 friendly flies

Spawns 6 friendly flies

Something's wrong

Spawns a pudde of slowing creep

The puddle lasts for much longer

I'm Drowsy

Applies slowness to all enemies and the player for the duration of the room

-

Gulp!

Destroyes the currently held trinket and applies its effects permanently to the player

-

Feels like I'm walking on sunshine!

Grants invulnerability for a short period of time

Grants the Gamekid item effect

Vurp!

Spawns the most recently used pill

Spawns the horse pill version of the recently used pill

Neutral Miscellaneous Effects

Name

Effect

Horse Pill Effect

I Found Pills

Cosmetic effect

Exaggerated cosmetic effect

Puberty

Cosmetic effect

Exaggerated cosmetic effect

Telepills

Teleports the player to a random room

-

Pheromones

Charms all enemies in the room for a short period

All enemies turn friendly

Re-Lax

The player spawns poops from themself for a short time

The player spawns poop from themself for a significantly extended period of time

One makes you larger

The player increases in size

The player's size increases twice

Horf!

The player fires an Ipecac-like shot out of themself, which deals 200 damage

The player fires a spray of the aforementioned shots

Negative Miscellaneous Effects

Name

Effect

Horse Pill Effect

Explosive Diarrhea

The player spawns five bombs from themself over the course of five seconds

The player spawns
multiple bombs from
themself, which home
in on enemies and
have a larger explosion
radius

Hematemesis

Empties all but one red heart container and spawns 1-4 red hearts

Spawns more hearts
alongside the base effect

Paralysis

Prevents the player from moving or shooting for 2 seconds

Effect lasts for 4 seconds

Amnesia

Applies the Curse of the Lost to the current floor

-

R U A Wizard?

The player fires diagonally for 30 seconds

The player fires
diagonally for
60 seconds

Addicted!

Turns all damage sources into full-heart damage sources for the duration of the room.

-

???

Applies the Curse of the Maze to the current floor

-

Retro Vision

Downscales all sprites for 30 seconds

Effect extended to 90 seconds

X-Lax

Spawns a puddle of slippery creep

The puddle lasts for much longer

I'm Excited

Drastically increases the speed of enemies and the player for the duration of the room.
The effect triggers again after 30 and 60 seconds after initlal use

-

Unlock methods

Pill effect

Unlock method

Percs!

Complete challenge #24

Addicted!

Complete challenge #24

Re-Lax

Complete challenge #25

???

Complete challenge #25

Feels like I'm walking on sunshine!

Unlock every entry in the Bestiary

Gulp!

Complete a Victory Lap via defeating The Lamb

Horf!

Participate in any way in 31 daily challenges

Vurp!

Obtain 50 items in a single run

Notes regarding pill effects

Pill effect

Notes

Health Down

Turns into a Health Up if the effect would kill the player otherwise

Health Up

Adds a soul/black heart for characters that cannot have red heart containers

Puberty

Taking three of these in a single run grants the Adult transformation

Pretty Fly

There is a max of three normal pretty flies, but the Big Fan familiars spawned by the horse pill have no upper cap

Stat up/down pills

The stat changes are affected by any stat multiplier the player may have, meaning the exact change values may not be exact

Telepills

Has a very small chance to teleport the player to the Ultra Secret Room

Hematemesis

No effect on characters that cannot have red heart containers.
Spawns the red hearts regardless, however.

One makes you larger

The Forgotten's bone club increases as well, giving the player an actual advantage.

Experimental Pill

Functions as a random stat increase if the player has PHD.
Functions as a random stat decrease if the player has False PHD

Character attributes

Name            

Properties                                                                                                              

Base          

Health

The amount of health the player has. Reaching 0 health kills the player.
There is a max of 12 hearts that the player can have at once.
(exception: having Birthright as Magdalene,
which increases the cap to 18 hearts)

The player's health can be made up of various types of hearts,
described in Pickups - Hearts

character
dependent

Speed

Determines how fast the player moves.
Expressed as a multiplier of the global base speed.

Has a minimum cap of 0.10 and a max cap of 2.00

1.00

Tear attributes

Name            

Properties                                                                                                              

Base          

Damage

The amount of damage your tears deal to entities.

There is a minimum cap of 0.50, and no maximum cap.

3.50

Fire Rate

Also called "tears" or "tear rate".

Determines how fast the player fires their tears.
Expressed in tears per second.

There are three soft caps, those being 5.00, 10.00 and 15.00,
which require increasingly more powerful items to break.

There is a hard cap of 120 tears per second.
Has a minimum cap of 0.01

2.73

Range

Determines how long your tears will travel before landing.
Expressed in grid tiles.

For reference, a standard room has an effective size of 12x7 tiles.

Has a minimum cap of 1.00

6.50

Shot Speed

Determines how fast your tears travel.
Expressed as a multiplier of the global base shot speed.

Has no effect on range.

Has a minimum cap of 0.60

1.00

Other attributes

Name            

Properties                                                                                                              

Base          

Luck

Affects room drops and tear effects.

The higher the luck, the more likely it is a room will drop
a pickup upon being cleared, and the more likely it is that
the player can fire a tear with a status effect assuming they
have the item that lets them do that in the first place.

Most status-effect-inducing items max out at 100% at 10.00-20.00 luck

0.00

Hidden attributes

Name            

Properties                                                                                                                                     

Knockback

Determines how much your tears knock entities back.

Affected only by the 7 Inch Nails, Pisces and Knockout Drops items.

Shot Height

Determines how high your tears are in the air.

Enough shot height can make your tears fly over obstacles.

Affected by various items

Pictured:
Comparison of minimum and maximum values for speed, fire rate, damage, range and shot speed

NOTE:
An underlined parameter means, it's better than default
A parameter in italic text means, it's worse than default
A star (*) near a parameter means, that it needs to be unlocked. The unlock requirement will not be listed, however.

Parameters below match Repentance values; if you don't own the Repentance DLC, you'll have different values, especially in terms of range.

Some characters have multiple types of health at start. Due to the size restrictions in the table, the health types will be abbreviated as follows:

Health type

Abbreviation

Red health

R

Soul/blue health

S

Black health

B

Bone health

K

Isaac
Available from start

Attributes                                                

Starting items                       

Starting abilities                       

Health:      ♥ × 3 Health type: red Speed:       1.00 Damage:      3.50 Tear rate:   2.73 Range:       6.50 Shot speed:  1.00 Luck:        0.00

► Bomb (x1)
► The D6*

none

Magdalene
Unlocked by having 7 or more red heart containers at once

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 4 Health type: red Speed: 0.85 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Yum Heart
► Full Health pill* (x1)

none

Cain
Unlocked by having 55 or more coins at once.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 2 Health type: red Speed: 1.30 Damage: 3.50 × 1.30 Tear rate: 2.73 Range: 4.50 Shot speed: 1.00 Luck: 1.00

► Lucky Foot
► Pill (x1)
► Paper Clip*

Can only fire from
his right eye

Judas
Unlocked by defeating the Satan boss.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 1 Health type: red Speed: 1.10 Damage: 3.50 × 1.35 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Coin (x3)
► Book of Belial

none

???
Unlocked by defeating the Mom's Heart boss 10 times total.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: soul Speed: 1.10 Damage: 3.50 × 1.05 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► The Poop

Cannot have red health.

Has an innate Lil Larva
ability; destroying a poop
spawns a blue fly.

Devil deal costs reduced
to 1 and 2 soul hearts for
light and heavy deals
respectively.

Eve
Unlocked by not picking up any hearts for 2 floors in a row.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 2 Health type: red Speed: 1.23 Damage: 3.50 × 0.75 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Dead Bird
► Whóre of Babylon
► Razor Blade*

The Whóre of Babylon
state removes the 0.75
damage multiplier,
effectively increasing
damage when active.

Samson
Unlock by completing 2 floors in a row without taking damage.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.10 Damage: 3.50 Tear rate: 2.68 Range: 5.00 Shot speed: 1.30 Luck: 0.00

► Bloody Lust
► Child's Heart*

none

Azazel
Unlocked by taking 3 items from devil deals in one run.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: black Speed: 1.25 Damage: 3.50 × 1.50 Tear rate: 3.23 × 0.27 Range: 4.50 Shot speed: 1.00 Luck: 0.00

none

Fires a short-ranged
Brimstone laser instead
of tears.

Has innate flight.

Lazarus
Unlocked by having 4 or more soul hearts at once

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 4.50 Shot speed: 1.00 Luck: -1.00

► Anemic*

Has an extra life, that,
when used, regenerates
on the next floor.

Lazarus' innate extra life
turns them into their
revived form upon death;
this form has increased
damage, speed and range.

For every death, the player
gets a permanent +0.5
damage bonus, but loses a
heart container
(this cannot bring the player
to 0 hearts though)

Eden
Unlocked by defeating Mom's Heart

Attributes                                                

Starting items                       

Starting abilities                       

Health: RANDOM Health type: RANDOM Speed: 1.00 ± 0.15 Damage: 3.50 ± 1.00 Tear rate: 2.73 ± 0.50 Range: 6.50 ± 1.50 Shot speed: 1.00 ± 0.25 Luck: 0.00 ± 1.00

► Random amount of
pickups

► Random active item

► Random passive item

► Random trinket

Costs a single
Eden Token to play.

Tokens are awarded after
beating Mom's Heart,
It Lives, the Beast, or
Ultra Greed.

The Lost
Unlocked by dying in a Sacrifice Room while holding the Missing Poster trinket

Attributes                                                

Starting items                       

Starting abilities                       

Health: none Health type: none Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Coin (x1)
► Holy Mantle*
► Eternal D6*

Cannot have health
of any kind; any hit
instantly kills the player,
unless it's absorbed
by a Holy Mantle shield
or any other form of
negating damage.

Starts out with flight
and spectral tears.

Lilith
Unlocked by defeating Ultra Greed as Azazel

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: 1R + 2B Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Box of Friends
► Cambion Conception
► Incubus (innate)

Cannot fire tears;
uses her Incubus to
deal damage instead.

Keeper
Unlocked by donating 1000 coins to the Greed Donation Machine

Attributes                                                

Starting items                       

Starting abilities                       

Health: ● × 2 Health type: coin Speed: 0.85 Damage: 3.50 × 1.20 Tear rate: 0.83 Range: 6.50 Shot speed: 1.00 Luck: -2.00

► Wooden Nickel*

Has an innate
triple shot.

Uses coins instead
of hearts as health.
Coins of any type
will regenerate any
empty coin containers.

Can have three innate
coin containers, but
the third one needs
to be unlocked first.

Apollyon
Unlocked by defeating Mega Satan

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Void

none

The Forgotten
Has a convoluted unlock method, described below:

To unlock the Forgotten, the player needs to unearth him from a Dirt Patch
in the Dark Room, using the Mom's Shovel item. Therefore, the player needs
to have beaten the Lamb and unlocked the Negative item before proceeding
with unlocking the Forgotten.

The shovel needed to dig up the Forgotten is split into two pieces, which
both need to be retrieved and put together before the player can unlock
the character.

The first piece requires the player to beat the Basement I boss in under
a minute of game time. After doing so, you will hear a muffled
"ISAAC", followed by faint thumping.

Afterwards, you need to come back to the spawn room. When inside,
a large shadow of a shovel handle will be visible. Placing a bomb and
letting it explode will drop the first shovel piece onto the floor, from
where it can be then picked up.

After picking up the first shovel piece, Mom's Foot will constantly attempt
to stomp you to death, with her attacks indicated by a growing
shadow appearing underneath your character.

The shovel piece itself is an active item, which, when used, will prevent
Mom's Foot from stomping the player for the duration of the room.
Make sure not to leave the shovel piece behind by replacing it with another
active item, as otherwise the shovel piece will disappear upon leaving the room.

With the first piece in your possession, you then need to complete Boss Rush.
Thankfully, the 20 minute restriction for Boss Rush is removed while you're
holding the shovel piece. Beating Boss Rush will grant the second piece,
which stops Mom's Foot from stomping the player for good.

Afterwards, you need to head to Sheol (you will be given no other choice
by the game), and then to the Dark Room, where there will be an empty
room with a single dirt patch, which can be dug up. Doing this unlocks
the Forgotten.

Attributes                                                

Starting items                       

Starting abilities                       

The Forgotten

Health: ♥ × 2 Health type: bone Speed: 1.00 Damage: 3.50 × 1.50 Tear rate: 2.73 × 0.50 Range: 6.50 Shot speed: 1.00 Luck: 0.00

Forgotten's Soul

Health: ♥ × 1 Health type: soul Speed: 1.30 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

none

Can switch between
their body and soul by
pressing CTRL. Both
have different stats,
but share items
between forms.

The soul has flight and
spectral tears, while the
body uses a melee attack
instead of regular tears.

The soul is chained to
the body, and thus has
a limited range of motion.

While playing as the soul,
the player can use the
body as a bullet sponge,
as it will turn invincible
as long as it isn't
controlled.

Bethany
Unlocked by defeating Mom's Heart/It Lives on Hard mode as Lazarus without dying once.

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Book of Virtues

Can't have soul
or black health;
those get transferred
to a special counter,
and are used as
auxiliary charges
for active items.

Jacob & Esau
Unlocked by defeating the Mother boss

Attributes                                                

Starting items                       

Starting abilities                       

Jacob

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 2.75 Tear rate: 3.00 Range: 5.00 Shot speed: 1.15 Luck: 1.00

Esau

Health: ♥ × 2 Health type: 1R+1S Speed: 1.00 Damage: 3.75 Tear rate: 2.50 Range: 8.00 Shot speed: 0.85 Luck: -1.00

none

The player controls
two characters at once,
both with their separate
stats and items that
need to be maintained
(the speed stat is
shared, however).

The player can press
CTRL to hold Esau in
place, and also to switch
between using active
items and consumables.

Tainted Isaac

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Bomb (x1)

The player can
carry only up to 8
passive items at
any given moment.

This limit gets extended
to 12 if the player has
Birthright in their
inventory.

Picking up items past
the limit will discard
the item selected
in the player's
inventory in the top
left corner of the UI.

Item pedestals will
passively switch
between 2 options
at a medium rate.

Tainted Magdalene

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 4 Health type: red Speed: 1.00 Damage: 3.50 × 0.75 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Yum Heart
(in consumable slot)

The player will
passively bleed out
all health past two
hearts, no matter
the type, at a rate
of half a heart per
10 seconds.

When the player is
bleeding, they
will leave red,
damaging creep on
the ground.

In exchange for this,
the player receives a
melee attack, that
activates upon touching
an enemy.

Enemies will often
drop flickering half
red hearts upon death.

Killing enemies with
the melee attack greatly
increases the chances
of the aforementioned
hearts dropping.

Tainted Cain

Attributes                                                

Starting items                       

Starting abilities                       

Health: 2 × ♥ Health type: red Speed: 1.30 Damage: 3.50 × 1.30 Tear rate: 2.73 Range: 4.50 Shot speed: 1.00 Luck: 0.00

► Key (x1)
► Bag of Crafting
(in consumable slot)

All pedestal items
disintegrate into
pickups when picked up,
forcing the player to use
the Bag of Crafting to
acquire items.

Tainted Judas

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 2 Health type: black Speed: 1.23 Damage: 3.50 Tear rate: 2.73 Range: 4.50 Shot speed: 1.00 Luck: 0.00

► Coin (x3)
► Dark Arts
(in consumable slot)

Can't have red health.

Tainted ???

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: soul Speed: 0.90 Damage: 3.50 Tear rate: 2.04 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Hold
(in consumable slot)

Can't have red health.

The player's bombs
and bomb pickups
get replaced with poop,
which comes in many
different types and can
be used as rudimentary
bombs.

The player will actively
spawn poop pickups
upon dealing enough
damage to enemies.

The player can store
up to 9 poops at once,
(29 w/ Birthright)
and can use the Hold
item to store one for
later.

Tainted Eve

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 2 Health type: red Speed: 1.00 Damage: 3.50 × 1.20 Tear rate: 1.20 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Sumptorium
(in consumable slot)

Firing for more than
2 seconds removes half
a heart from the player's
health bar and spawns a
blood clot, that mimics the
player's movements and
firing.

The player can use the
Sumptorium item to suck
up all existing clots, and
regain health from them.

Tainted Samson

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.50 Range: 5.00 Shot speed: 1.00 Luck: 0.00

none

The player actively
builds up "berserk" by
taking damage and
dealing damage to
enemies.

The current state of
berserk is indicated
by the red tint of
the character's sprite.

Entering the berserk
state grants the player
+0.40 speed, +0.75
fire rate, +3.00 damage,
and restricts their firing
mode to a jawbone melee
weapon.

This state lasts for 5
seconds, and each
enemy killed during
it extends it by 1
second.

The berserk state
also lets the player
live at 0 health, as
long as they keep
this state going.
Otherwise, the player
will need to find health
before it ends, as not
doing so will kill the
player as normal.

Tainted Azazel

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: 0R + 3B Speed: 1.00 Damage: 3.50 × 1.50 Tear rate: 0.91 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► The Fool tarot card (x1)

Has an innate, light
version of Brimstone,
which has unlimited
range, unlike regular
Azazel's, but has around
half the damage output
of regular Brimstone.

Charging the laser will
make the player sneeze.
This sneeze afflicts any
enemies in range with
a debuff, which makes
them significantly more
vulnerable to the player's
Brimstone. Hitting enemies
with the sneeze also
reduces the laser's charge
time.

Enemies that die with
the debuff still on them
will spread it to any
nearby enemies.

Tainted Lazarus

Attributes                                                

Starting items                       

Starting abilities                       

Alive Lazarus

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 4.50 Shot speed: 1.00 Luck: 0.00

Dead Lazarus

Health: ♥ × 2 Health type: soul Speed: 0.90 Damage: 3.50 × 1.50 Tear rate: 2.50 Range: 6.50 Shot speed: 1.00 Luck: -2.00

► Flip
(in consumable slot for
both forms)

Each room clear
switches the player
between their
dead and alive
forms.

Each form has
different inventories
and stats, with only
pickups being shared.

The player can use
the Flip item to
flip between forms
at will.

All pedestal items
will have a faded
version behind them,
acquirable after flipping,
manually or automatically.

Tainted Eden

Attributes                                                

Starting items                       

Starting abilities                       

Health: RANDOM Health type: RANDOM Speed: 1.00 ± 0.15 Damage: 3.50 ± 1.00 Tear rate: 2.73 ± 0.50 Range: 6.50 ± 1.50 Shot speed: 1.00 ± 0.25 Luck: 0.00 ± 1.00

► Random amount of
pickups

► Random active item

► Random passive item

► Random trinket

Taking damage will
reroll the player's items.

Self-inflicted damage
will not trigger this effect.

Tainted Lost

Attributes                                                

Starting items                       

Starting abilities                       

Health: none Health type: none Speed: 1.00 Damage: 3.50 × 1.30 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Holy Card (x1)
► Coin (x1)

Cannot have health
of any kind; any hit
instantly kills the player,
unless it's absorbed
by a Holy Mantle shield
or any other form of
negating damage.

Has flight and spectral
tears.

Defensive, or otherwise
useless items are
prohibited from spawning.

Each card has a 10%
chance to be replaced
with a Holy Card.

Tainted Lilith

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: 1R + 2B Speed: 0.85 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

none

Can't fire tears;
uses a fetus-like
familiar to attack
instead.

The familiar deals
both contact damage
and ranged damage

Tainted Keeper

Attributes                                                

Starting items                       

Starting abilities                       

Health: ● × 2 Health type: coin Speed: 1.00 Damage: 3.50 Tear rate: 0.99 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Bomb (x1)

Starts out with
an innate quad shot.

Health works along
the same principle
as when playing
regular Keeper.

All pedestal items,
with the exception
of story items, cost
15 cents (heavy devil
deals will cost 30 cents).

Enemies often drop coins
on death, which fade out
after a short time. The
coins dropped can be
of any type.

Tainted Apollyon

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 2 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 1.82 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Abyss
(in consumable slot)

none

Tainted Forgotten

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: soul Speed: 1.10 Damage: 3.50 × 1.50 Tear rate: 1.36 Range: 6.50 Shot speed: 1.00 Luck: 0.00

none

The player exists
as two enities;
the soul and the
body.

The soul cannot
attack, and instead
throws the body
around to deal
damage, and to
interact with the
world.

The body is invincible,
and blocks projectiles.

Tainted Bethany

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: soul Speed: 1.00 Damage: 3.50 Tear rate: 2.73 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Lemegeton
(in consumable slot)

Can't have red health;
uses it as auxiliary charge
for active items instead.

Tainted Jacob

Attributes                                                

Starting items                       

Starting abilities                       

Health: ♥ × 3 Health type: red Speed: 1.00 Damage: 3.50 Tear rate: 3.00 Range: 6.50 Shot speed: 1.00 Luck: 0.00

► Anima Sola
(in consumable slot)

Roughly 30s after
the player spawns,
Dark Esau will come
out of the floor and
proceed to chase the
player, charging at
them whenever close.

Dark Esau deals
extreme contact damage
to enemies, and turns
the player into a character
akin to the Lost on contact
with the player.

When turned, the player
is granted flight, spectral
tears, and will die in one
hit from anything.

The player will return to
normal upon travelling
to another floor.

Birthright - Normal Characters

Character                    

Effect                                                                                                                   

Isaac

All future item pedestals will cycle between two options

Magdalene

Adds one full red heart container and increases the max
amount of hearts the player can have to 18

Cain

+1.00 luck.
Arcades have more machines on average.

Judas

If the player is not currently holding The Book of Belial, they receive it.

The Book of Belial becomes a passive item that can be held
beneath other active items, similar to Book of Virtues.

The damage boost received from The Book of Belial
scales with the amount of charges the active item above
it has (may not work or work incorrectly with one-time use
items, timed recharge items and unlimited use items).

When stacked with Alabaster Box, it allows black hearts
to count towards charging the box and changes the final
reward to be black hearts and items from the Devil Room pool.

???

Health-ups from items are doubled in strength

Eve

Whóre of Babylon and Dead Bird are always active
regardless of the player's status

Samson

Samson's Bloody Lust can proc 4 more times

Azazel

The player's brimstone beam becomes much wider.
No effect on damage

Lazarus

Grants a +21.60 damage bonus, which fades out
over the course of one minute.
The boost is reapplied every time the player dies and
respawns using the innate extra life.

Eden

Spawns three items pulled from random pools.
The player can only choose one, as the others
will disappear upon doing so.

The Lost

Prevents most of the items, which would be
useless when playing as the Lost, from spawning

Lilith

The player's familiars (including the default Incubus)
will attempt to position themselves in front of the player when firing.

Keeper

Adds one more coin container

Apollyon

Using Void can sometimes respawn an item
previously sucked up by it, whilst regaining the buffs provided by it.

The Forgotten

The Soul becomes unchained, and is able to move freely.
The Forgotten's body can be left behind, and switching back will
teleport the player back to it, regardless of the status of the room.

Bethany

Activating an item using soul charges will sometimes
not consume the charges.

Jacob & Esau

The brother which picked up the item gains copies
of three of the other brother's passive items

Birthright - Tainted Characters

Character                    

Effect                                                                                                                   

Tainted Isaac

Adds 4 more slots for passive items

Tainted Magdalene

The player stops bleeding at 3 hearts instead of 2

Tainted Cain

The amount of pickups spawned from picking up items is doubled.

Tainted Judas

Extends Dark Arts' range of effect

Tainted ???

The player is now able to hold 29 poops instead of 9

Tainted Eve

Red Heart blood clots spawn flickering half heart pickups after they die.
These pickups will disappear after two seconds.

Tainted Samson

The timer is recharged by 3 seconds instead of 1,
when the player kills an enemy during berserk mode.

Tainted Azazel

Doubles the size of the player's sneeze attack

Tainted Lazarus

The player's currently inactive form will turn into a ghost,
that sits alongside the player and fires with them.
The ghost is invulnerable.

Tainted Eden

Items acquired prior to picking up Birthright will not be
rerolled when the player takes damage.
Same goes for the player's base attributes.

Tainted Lost

Grants an extra life, which resurrects the player in the same room

Tainted Lilith

Familiars that normally follow Tainted Lilith will instead
act like her innate Gello familiar

Tainted Keeper

Coins spawned by enemies are pulled towards the player

Tainted Apollyon

Holding down the fire button make the locusts deal continuous
damage to enemies instead of returning to the player
every now and then.

Tainted Forgotten

The player is now able to retrieve the body from a distance,
using the Recall item in the consumable slot.

Tainted Bethany

Spawns 4 random item wisps with very high HP

Tainted Jacob

Splits Dark Esau into two copies of itself. Both Esaus will
always charge at the same time and one will not charge if the
other is not in position.
Using Anima Sola chains both Dark Esaus at once and forces
them together into one spot. Subsequent uses release each
Dark Esau one at a time.

First, the game determines the amount of rooms the floor will contain. The deeper you go, the more rooms will generate.

Playing on Hardmode increases the amount of rooms by 2-3, and the Curse of the Lost by 4.
Both of these effects can stack, increasing the room amount by 6-7 in total.

Afterwards, the game determines how many dead ends will generate. Each floor must have at least 6 dead ends (with the exception of Basement I, which has a minimum of 5).
The amount of dead ends increases:

• by 1, if the floor is an XL floor (Curse of the Labyrinth)
  
• by 2, if the floor is the Void
  
• by 1, if the player has the Voodoo Head item

Then, the game generates special rooms in the aforementioned dead ends, starting from the dead end farthest from the spawn point. Should there be less special rooms available than the amount of dead ends, the game will not attempt to spawn any more special rooms. This is most prominent in floors like the Chest, Dark Room, where completely featureless dead ends are a common sight.

The game has a priority list of special rooms, that it goes through when inserting them into the floor. The list goes as follows, starting from top priority:

1. Boss Room
Always generates

2. Super Secret Room
Always generates.
Generates 2 SSRs if the player has the Luna item.

3. Shop
Generates in chapters I-III.
Can generate in chapters IV and V if the player has specific trinkets.

4. Treasure Room
Generates in chapters I-III.
Can generate in chapters IV and V if the player has specific trinkets.

5. Planetarium
1% base chance to generate in chapters I-III.
The chance can be increased by not visiting Treasure Rooms.

6. Sacrifice Room/Dice Room
14% chance to generate by default. Increases to 36% if the player's health is equal to or greater than the amount of their heart containers.
If a Sacrifice Room generates, it has a 2% chance to be replaced by a Dice Room. This chance increases to 22% if the player has more than 1 key.

7. Library
Has a 5% chance to generate.

8. Curse Room
50% chance to generate.
Increases to 63% if the player has entered a Devil Room previously in the run.
Possessing the Voodoo Head item will make 2 Curse Rooms generate.

9. Miniboss Room
25% chance to generate, and a 44% chance on floors past Basement I

10. Challenge Room
50% chance to generate if the player's health is equal to or exceeds the amount of heart containers they have.
Will generate as a Boss Challenge Room should it appear on the second floor of a chapter.

11. Arcade/Vault
Generates on the second floor of a chapter if the player has 5 or more coins.
If an Arcade generates, it has a 10% chance to be replaced by a Vault.
This chance increases to 40% if the player has more than 1 key.
The Vault will still be able to spawn should the player have more than 1 key but less than 5 coins.
If the player does not meet the conditions for the Vault to spawn, and the game rolls the 10% chance, the Arcade will not generate either.

12. Bedroom
2% chance to generate in chapters I-III.
Increases to 22% if the player has less than two red hearts, or less than two hearts in general, should they not have any red hearts.

13. Secret Room
Always generates.
Two Secret Rooms will generate if the player has the Fragmented Card trinket or the Luna item.
Three Secret Rooms will generate if the player has both.

  The first chapter.

  Chapter 1 floors are typically very small in size,
  and contain simple, fragile enemies.

  They serve as a means of getting the player geared
  up for the later chapters.

  In the first floor of Chapter 1, the Treasure Room
  and the Shop will be unlocked and free to access.
  From the second floor and onward, however, the
  rooms will be locked, and will require a single key
  to open.

  In addition, a Deal Room won't be able to spawn
  on the first floor, being able to spawn only on further
  floors. The room can still be accessed, however, by
  the means of a Joker card or any similar effect.

  There are 5 different Chapter 1 floors, with only the
  Basement being unlocked by default.

The first and most iconic floor in the game.

The Basement contains simple enemies, most of them relying on contact to damage the player. The bosses of the floor are fairly simple as well, having a limited attackset and basic movement.

An alternate version of the Basement, unlocked by defeating all Chapter I bosses at least once

Most enemies in the Cellar tend to be spider-related, but normal Basement enemies aren't a rare sight either. This usually makes the Cellar more of a slog to get through, but not always.

In addition to the enemies, cobwebs will appear in some rooms, slowing the player down should they step on them

The Cellar's boss pool is slightly different from the Basement's, featuring additional spider/ghost-themed bosses, mainly the Widow, the Haunt, Blighted Ovum and Pin.

An alternate version of the Basement, unlocked by defeating Mom's Heart 11 times

The floor is themed around fire, and so are its enemies. A burning enemy is a fairly common sight in this floor, and they will usually be slightly weaker than their base version or signifcantly more annoying and tiresome to deal with, no in-between.

Unlike the Cellar, the Burning Basement does not have unique bosses.

An alternate-path version of the Basement, unlocked by defeating Hush three times in total.

The water-themed Downpour is a completely different floor from the Basement. It's accessed via the door, that spawns after defeating the boss in any floor of Chapter I. It requires a single key to open.

The enemies inside Downpour are slightly more complex, and usually rely on projectiles to damage the player.

Downpour II contains a special mirror room, used in the Repentance puzzle (see 'Floors - Unlocking the Corpse' for more info)

The floor has some special visual effects, mainly the flooded floor and the occasional lightning strikes. They aren't purely visual, however, as the water can synergize with electricity-generating items, such as 120 Volt and Jacob's Ladder, while the lightning strikes reveal any Wraiths that are in the current room.

Downpour has its own, unique boss roster; no Basement/Cellar bosses can appear in Downpour and vice versa. Some of this floor's bosses are shared with Dross though.

An alternate version of Downpour, unlocked by defeating all Downpour bosses at least once.

The sewage-themed Dross is a harder version of Downpour. Its enemies rely on both erratic movement, and projectiles to damage the player.

Some rooms in this floor may have an active current running through them, hindering the player's movements slightly, but also enemies' movement. Most rooms with currents are of the standard size, but large rooms with currents may rarely appear.

The floor contains a few bosses from Downpour, and a few of its own, mainly Clog, Colostomia and Turdlet.

The floor has some special visual effects, mainly the flooded floor and the toxic gas in the background. The water synergizes with electricity-generating items the same way it does in Downpour. The gas is purely cosmetic.

Dross, being the alternate version to Downpour, also contains the Mirror Room in its second floor.

  The second chapter.

  As visible to the left, 2nd chapter floors are
  slightly larger than 1st chapter floors.

  The enemies of this chapter are noticeably tankier
  than the previous one's, and the same can be said
  for the bosses (Mega Fatty literally has almost
  as much HP as Mom).

  From this chapter and onward, Greed will be able to
  spawn in Shops and Secret Rooms, replacing their
  contents.

  There are 5 different Chapter 2 floors, with only the
  Caves being unlocked by default

The default floor of the second chapter.

There's nothing that can be said about the Caves that hasn't been said in the chapter introduction, just expect tanky enemies and bosses alike.

An alternate version of the Caves, unlocked by defeating all Caves bosses at least once.

The Catacombs' theme is focused around rot and decay, featuring enemies appropriate for these themes.

The floor's got some unique bosses, mainly the Husk, the Hollow, the Wretched and the Carrior Queen, all themed around decay, except for the Dark One and Polycephalus, that are just there.

The floor also has bosses which are shared with the Flooded Caves, those being the Forsaken and the Frail.

The biggest (and probably the only) upside about the Catacombs is that it doesn't contain Mega Fatty (unless you roll the 1 in 32768 chance of getting a Double Trouble, in which case you might get a Double Trouble containing Mega Fatty)

An alternate version of the Caves, unlocked by defeating It Lives! 16 times total.

The Flooded Caves' theme is, as the name might suggest, focused around water, featuring bloated enemies and an increased amount of airborne enemies.

The floor contains additional visual effects, mainly the flooded floor and the ever-present blue fog/tint.

The alternate-path version of the Caves, unlocked by defeating Hush three times total.

After unlocking this floor, clearing the boss room of any Caves floor or its variants (also the Downpour II boss room) will spawn the entryway to the Mines. The door to the Mines will always be boarded up, and will require two bombs to unlock.

The enemies in this floor are mainly themed around explosions and fire.

The floor features some unique environmental objects, such as throwable bombs, enemies in minecarts, or dark rooms.

Mines II contains the minecart room used in the Repentance puzzle. This room only spawns when the player has the first knife piece — it will not spawn otherwise.

The bosses of this floor, just like in Downpour, are completely unique, meaning they can't appear in the Caves and vice versa. Some of this floor's bosses are shared with Ashpit, however.

An alternate version of the Mines, unlocked by defeating all Mines bosses at least once.

The ash-themed Ashpit is a harder version of the Mines, featuring tankier, and heavier-hitting enemies, mainly themed around skeletons, ghosts, fire, and the titular ash.

The floor contains some unique, purely cosmetic visual effects, mainly a continuous stream of ash running through the screen.

The Ashpit, being a variant of the Mines, contains the same unique environmental objects as the Mines. The minecart room also follows the same spawning rules.

  The third chapter.

  Chapter 3 is the first real damage check of the run;
  if you have base stats by the time you enter this
  chapter, you're gonna be having a hard time
  getting through its floors.

  In addition to tankier enemies, the floors of
  chapter 3 will contain an increased amount of
  trap rooms, some of which can be really
  difficult, if not impossible for newer players.

  The boss of the second floor is always Mom.

  After defeating Mother, a Strange Door will
  spawn in the spawn room of every Chapter 3 floor
  (except for the Mausoleum and Gehenna). This
  door is used in the ascension sequence
  (see 'Floors - Ascension')

  There are 5 different Chapter 3 floors, with only the
  Depths being unlocked by default

The default Chapter 3 floor.

The enemies inside the Depths are relatively on par in terms of health with the enemies from the Caves, but they use more complex attacks. The difficulty in this chapter usually comes from tight room layouts, or rarely enemy spam.

An alternate version of the Depths, unlocked by defeating all Depths bosses at least once.

Just like the Catacombs compared to the Caves, the Necropolis isn't much different from the Depths, featuring enemies related to death and skulls, and also slightly more trap rooms, making it a harder variant of the Depths overall.

The floor's got a few unique bosses, mainly the Adversary, the Mask of Infamy, and also the Bloat & the Pile, both of which are also shared with the Utero and Ashpit respectively.

An alternate version of the Depths, unlocked by defeating It Lives 21 times.

The Dank Depths feature many tar-themed enemies, which tend to be tankier, and will usually excrete slowing creep, making the Dank Depths a step-up in difficulty from the regular Depths, albeit not a big one.

An alternate-path version of the Depths, with its access door unlocked by beating Hush three times total.

After unlocking this floor, clearing the boss room in the first floor of Chapter III or in Mines/Ashpit II will spawn the doorway leading to the Mausoleum. It requires the player to sacrifice two full hearts to open it (The Lost and his tainted version can open the door for free). The door can also be opened by a few select items, such as Dad's Key, Sharp Key, Mr. ME!, etc.

The enemies in the Mausoleum use much more complex attacks than the ones in the Depths, increasing the difficulty of the floor by a noticeable amount.

The floor additionally contains a few environmental objects of its own, including Teleporters and Grudges, both described in the Environment category of this guide.

The bosses inside the Mausoleum are very complex, requiring a fair bit of experience with them to be able to take them on without taking any damage.

Just like in the Depths, the boss of Mausoleum II is always Mom.
In the Mausoleum though, a special, harder variant of Mom spawns, which is much more aggressive and has slightly more complex attacks. More information on this version of Mom can be found in Final Bosses - Mom.

An alternate version of the Mausoleum, unlocked by defeating all Mausoleum bosses at least once.

The torture-themed Gehenna is a harder version of the Mausoleum, with the difficulty spike being more noticeable than with the other alt-path floors.

The Gehenna also features a unique enviromental object: the Ball & Chain, described in Environment - Other

  The fourth chapter.

  The game really steps up in difficulty from this point
  onward, featuring tankier enemies, giant floor layouts,
  and introducing gameplay modifiers that make the game
  harder.

  From this chapter and onward, the player will take a full
  heart of damage from all sources. This can be brought
  down to just half a heart, if the player has the Wafer item.

  In addition to the damage modifier, Treasure Rooms,
  Shops, and Planetariums stop spawning, unless
  the player acquires the trinkets that can make them
  spawn again. When taking the floor generation formula
  into account, this also means that there will be many more
  dead ends than in the previous chapters.

  The boss of the second floor is always Mom's Heart, or
  It Lives!. The exception to this is the Corpse, the boss
  of which will always be Mother

  There are 4 different Chapter 4 floors

The default Womb floor, unlocked by defeating Mom for the first time.

As with the Caves, there isn't much that can be said that wasn't said in the introduction to the chapter.

An alternate version of the Womb. Unlike other floor variants, the Utero starts out unlocked by default, thus technically sharing unlock conditions with the Womb.

The floor doesn't differ much from the Womb, with the only real difference being the slightly different enemy roster, featuring enemies with deformed bodies.

The Utero has a few unique bosses, including Teratoma, Daddy Long Legs, and also Sisters Vis, the Bloat and Triachnid, which are shared with other floors.

An alternate version of the Womb, unlocked by defeating It Lives 30 times total.

Doesn't differ much from the Womb aside from the different enemy roster, featuring more scarred/deformed enemies.

An alt-path version of the Womb, which needs to be unlocked through a sophisticated process, described in detail in Floors - Unlocking the Corpse

The decay/rot-themed enemies inside the Corpse are much more complex and tanky, amping up the difficulty by a few, very noticeable notches.

The Corpse can be entered only from Mausoleum/Gehenna II.

The Corpse additionally contains a unique environmental obstacle, that being the Spikeball, described further in Environment - Other

Unlike in any other chapter and floor, the bosses in the Corpse are straight up unfair; expect to die a lot on your first couple of tries with them.