- This article refers to the item Abaddon. For the character with an alternate name for the Biblical demon of the same name, see Apollyon.
Abaddon is an unlockable passive item. It appear as a red pentagram.
- Gives Isaac 6 black hearts and remove all red heart containers.
- 1.5 damage up.
- 0.2 speed up
- Gives a chance of shot.
- Fear tear effect depends on the Luck stat, and goes up to 100% at 85 Luck.
- Since Isaac can't gain health of any kind once the maximum of 12 hearts is reached, having 12 heart containers will grant him no black hearts, then remove his entire health and subsequently kill him.
- Does not remove Soul Hearts.
- Will kill Keeper (character) as he cannot have black hearts. It will spawn lots of flies though.
- Has no negative trade-off when taken as ???, except the fact of an Angel Room being unable to appear for the remainder of the run.
- The item is named after the demon Abaddon (also known as Apollyon) from the book of Revelation of the Bible.