Key Bum is an unlockable passive item added in Afterbirth.
Effects[]
- 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.
Notes[]
- Key Bum will not pick up golden keys.
Key Bum will pick up charged keys without additional benefit.
- Key Bum will leave a Lil' Battery behind when picking up charged keys.
Synergies[]
- BFFS!: Familiar is bigger and drops chests more often.
- Flat Penny: Chests frequently contain pennies, which have a chance of spawning more keys for Key Bum to pick up, possibly lead to a loop.
- Gilded Key / The Left Hand: Works as expected.
- Guppy's Eye: Allows Isaac to choose which Locked Chests are worth opening and which to pass, thus saving keys. Great for min-maxing.
In-game Footage[]
Trivia[]
- This item is the Key Master counterpart of Bum Friend and Dark Bum
Seeds[]
PC WJK1 9R0Z (Treasure Room adjacent to spawn)
Bugs[]
 Bug!
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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. |
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| Bug!
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 Charged Keys do not increment Key Bum's key count when picked up.
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 Lazarus Unlocks 
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 Ultra Greed Unlocks
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 The Binding of Isaac: Rebirth
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