Key Bum is an unlockable passive item added in Afterbirth.
- Spawns a familiar that follows Isaac around and collects keys, dropping random Chests in return. (He does not fill up a familiar "slot".)
- This item belongs to the Super Bum set. Collecting three items from this set will transform Isaac's bums into Super Bum.
- BFFS!: Familiar is bigger and drops chests more often.
- The Left Hand/ Gilded Key: Works as expected.
- Flat Penny: Chests frequently contains pennies, which have a chance of spawning more keys for Key Bum to pick up, possibly lead to a loop.
- Guppy's Eye: Allows Isaac to choose which Locked Chests are worth opening and which to pass, thus saving keys. Great for min-maxing.
PC WJK1 9R0Z (Treasure Room adjacent to spawn)
||If Credit Card is used in a Shop with keys, Key Bum will not be able to pick up the free keys. This can be fixed if Isaac leaves and re-enters the shop.
|| Charged Keys do not increment Key Bum's key count when picked up.