v1.3:

Changes:
- Pocket of Flies now grants the player 2 Red Heart Orbital Flies after purchasing a Devil Deal of any kind.

Fixes:
- Fixed EID descriptions of certain items and trinkets flickering
- Fixed Fiend Folio's Jack of Hearts instantly killing Duke and Tainted Duke on use.

v1.2?

Additions:
- Support for Fiend Folio and REP+ mods! This means support for 20 new heart types and 8 new unique flies and spiders to collect!

v1.1:

Additions:
- Support for Ugh for Bad Items

Balance Changes:
- HP CAP IS NOW 3 SOUL HEARTS :)
- Duke and Tainted Duke will now convert Heart Containers into Soul Hearts instead of Red Flies, giving them much more opportunities to regain HP.
- Tainted Duke's Rotten Gullet damage now scales with damage stat, giving it more viability late-game.

Bugfixes:
- Fixed Tainted Duke dying infinitely after picking up Dead Cat
- Fixed 1 and 2 Soul Heart prices not being replaced with fly/gullet prices
- Fixed Tainted Isaac's pedestals not cycling if one of the items is a locked Duke item
- Fixed Duke and Tainted Duke being able to pick up a Heart without the other pickup disappearing with Options?
- Fixed Tainted Duke's head exploding and disappearing when using Rotten Gullet after a save/continue
- Fixed Berkano rune effect popping up when playing Giantbook animations from other mods
- Fixed Web Hearts being able to heal Soul Hearts in some specific scenarios
- Fixed The Nail being able to remove Soul Hearts in some specific scenarios
- Fixed Tainted Duke's Gullet charges not showing the content when using Fiend Folio or Repentance Plus

Other Tweaks:
- Soul of Duke is now categorized as a Soul in Encyclopedia
- Duke's Gullet and Rotten Gullet no longer have all-caps names in EID
- Tainted Duke's devil prices now better reflect that his charges act as currency

This update does NOT add compatibility for custom hearts added in Fiend Folio or Repentance+, that will be the next update! :)