Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki

Bob's Brain is a passive item.


  • Spawns a familiar that can be fired towards enemies as a projectile.
    • Removed in AfterbirthBob's Brain is fired directly from where Isaac is standing.
    • Added in AfterbirthBob's Brain is fired directly from where it is located in the chain of familiars behind Isaac, making aiming it slightly more difficult.
  • If it hits an enemy, it deals 3.5 damage and explodes, further damaging and poisoning monsters.
    • Removed in Repentance The explosion deals 60 damage.
    • Added in Repentance The explosion deals 100 damage.
    • Added in Repentance The explosion ignores armor.
    • The poison deals double Isaac's damage over time.
  • The explosion can hurt Isaac, dealing a full heart of damage.
    • This can make picking up the item a risky choice, as Bob's Brain will always fire, regardless of whether or not Isaac will be caught in the explosion.
  • Once it explodes, it takes a few seconds to re-appear.
  • Added in Afterbirth This item belongs to the Bob set. Collecting three items from this set will transform Isaac into Bob.


  • Bob's Brain is affected by most bomb modifiers.
  • Bob's Brain only explodes when hitting an enemy, and does not explode upon hitting a fire, poop, or wall. It can destroy poops and fires like normal shots, however.
  • Bob's Brain never launches immediately upon entering a room unless a tear-firing key is released and pressed again, or until several seconds have passed.
  • It is possible to get multiple Bob's Brains to spawn on the same floor by finding one in a Locked Chest and not taking it
    • Only one copy of the brains will be active at a given time, with another one firing immediately after the first has exploded or starts to return from a miss.
    • Removed in Afterbirth Multiple copies of Bob's Brain will float in the same spot in the familiar line.
    • Added in Afterbirth Each copy takes up their spot on the familiar line, but only the first one launches out. Respawning brains may end up stacking on top of each other.


  • BFFS! BFFS!: The impact damage is increased to 7 and the explosion deals an additional 25 damage.
  • Mr. Mega Mr. Mega: The explosion deals an additional 85 damage.
  • Sad Bombs Sad Bombs: Bob's Brain will fire tears upon exploding.
  • Added in RepentanceBrimstone Bombs Brimstone Bombs: Brimstone beams will shoot out upon exploding.


  • Bobby-Bomb Bobby-Bomb: No effect.
  • Added in AfterbirthBomber Boy Bomber Boy: Explosion damage is halved, with no additional explosions.
  • Added in Afterbirth †Duct Tape Duct Tape: Bob's Brain stays in place relative to Isaac until it is fired.
  • E. Coli E. Coli/Flush! Flush!: Bob's Brain will explode upon hitting an enemy that has been turned into poop.

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