Importante note: using REPENTOGON[repentogon.com] should largely avoid this sort of issue.

Due to issues in the way Isaac downloads Steam Workshop mods with a large download size, a lot of users report strange errors the first time they install the mod or download a major update, which are caused by missing files.
To fix this, try redownloading the mod by:
-Closing the game
-Deleting the mod's folder (found in <steamapps Isaac game folder>/mods/revelations_2880387531)
-Restarting the game
If you had download issues, it should be fixed by doing this. This should fix 99% of the major bugs found after first installing the mod.
If it doesn't work, try our download mirror instead, found here[github.com].

(Posted as separate thread to avoid clogging up the main page, especially with the character limit)