Was browsing the latest Steam event thing and saw this game and it caught my eye! Twelve hours later I've beaten the demo. Unlocked one of the two bonus classes too.

Things I'd like to suggest and I'm not sure if you plan on doing already:
(Take them with a grain of salt, I'm not a game dev.)

A second item slot for each character. I can see how that might break the game pretty quickly. But I think it will make building characters A LOT more fun. Maybe make enemies harder to compensate?

A way to get more of the unit type bonuses easier. I have two suggestions for this.
1. Let us combine units of the same color to upgrade them. Maybe also have a storage for units we're not using so I don't have to just fill my entire party with things I don't want.
2. Randomize the emblem you get from each unit from their pool. Like instead of the druid (or whatever they're called) always giving nature as a common, instead it randomly picks from it's pool of three. And then the rare version would pick two of them from it's pool of three. While the legendary variant would just have all three still.

Non-eqiuppable relics. Things that just buff your entire party that you hold onto during a run. Could be an alternative to additional item slots on characters?

Bosses. I know there will be a final boss, but I'm not sure if you plan on others. I'd like to see some!

Alternate Skins/Colors for units. Just a fun little thing that might also help people distinguish between their units if they're running teams with multiple of the same type.

Overall, I really enjoyed the demo and will definitely be buying the game when it comes out!