Binding of Isaac: Rebirth Wiki

Rotten Baby is a passive item.

Effect[ | ]

  • Spawns a familiar which spawns friendly Blue Flies in a room with monsters when Isaac holds down a fire key.
    • The initial blue fly will target a monster once nearby, in which Rotten Baby will lock its blue flies automatically onto the same one, immediately heading towards and damaging it until it dies.
  • (except in Rebirth) This item belongs to the ConjoinedConjoined set. Collecting three items from this set will transform Isaac into a three-faced version of himself.

Notes[ | ]

  • Spawns one Fly at a time.
  • Blue Flies deal 2x Isaac's damage.
  • Flies will be generated regardless of Isaac's ability to fire tears normally.
  • (in Repentance) Familiars that follow behind Isaac have a certain priority in how close their position is to him over other familiars, with Rotten Baby having the lowest priority at 6th and thus being farther from Isaac than familiars of different priorities.
  • (in Repentance) Rotten Baby can rarely drop from polyps in the CorpseCorpse.

Synergies[ | ]

  • (in Afterbirth † and Repentance)Fish TailFish Tail: Rotten Baby will spawn two flies at a time.
  • Collectible Mongo Baby iconMongo Baby: Mongo Baby will also spawn flies.

Interactions[ | ]

  • Collectible BFFS! iconBFFS!: Rotten Baby becomes larger, but this is only a cosmetic change.
  • Collectible Hive Mind iconHive Mind: Fly damage is doubled.
  • (in Repentance)The TwinsThe Twins: Unlimited flies can be slowly generated by walking back and forth between rooms while firing. A new fly will generate each time Rotten Baby is duplicated.

In-game Footage[ | ]

Trivia[ | ]

  • This item is used in The Family Man (challenge #19).
  • Even though the right side of Rotten Baby's face is decayed, when his sprite faces left, his left side appears decayed as well.

Bugs[ | ]

Bug Bug! PC Rotten Baby will be able to spawn more than one friendly fly if the run is left and then resumed.