Binding of Isaac: Rebirth Wiki

BFFS! is a passive item.


  • Visually increases the size of all familiars by 25%, and improves the effectiveness of most of them.
    • Doubles the damage of Familiars that deal damage through tears and contact damage.
      • Has no effect on Creep generated by familiars.
    • For pickup-generating familiars, increases the frequency that they drop pickups.
      • Familiars that require clearing a certain number of rooms will require one less room.
      • Familiars that have a random chance to drop items have a higher chance.
      • Familiars that pick up consumables require less, except Dark Bum Dark Bum which is unaffected.
    • Some familiars have unique synergies.


  • The size change is only cosmetic: familiars' hitbox for blocking damage or attacking is not affected.
  • Familiars summoned by a trinket or by Monster Manual Monster Manual are also affected by BFFS!.
  • The Blue Flies and Blue Spiders benefit from Hive Mind Hive Mind instead.
  • Does not increase the frequency or effectiveness of Status Effects applied by familiars.


  • BBF BBF/Bob's Brain Bob's Brain: Doubles impact damage and increases explosive damage by 25.
  • Added in RepentanceBird Cage Bird Cage: Spawns 4 rock waves in an x pattern. Doubles the damage when the bird lands and doubles contact damage. Damage of waves unaffected.
  • Added in RepentanceBlood Oath Blood Oath: Adds 2 extra full hearts worth of bonuses if any health is drained.
  • Added in RepentanceHoly Water Holy Water: Double water damage, spawn a blue flame at point of impact.
  • Added in AfterbirthIncubus Incubus: Shoots tears that do Removed in Repentance 2x Isaac's damage Added in Repentance 1.5x Isaac's damage. Still deals 2x as Lilith Lilith.
  • Added in RepentanceIsaac's Heart Isaac's Heart: Fires additional shots in random directions and leaves a larger puddle of creep. Does not change the heart's size.
  • Juicy Sack Juicy Sack: Spawns an extra Blue Spider.
  • Added in Afterbirth †Lil Spewer Lil Spewer: Increases the creep pool's size, but not its damage.
  • Added in RepentanceLost Soul Lost Soul: Gives the Lost Soul a Holy Mantle Holy Mantle effect.
  • Added in Afterbirth †Mystery Egg Mystery Egg: Spawns a champion variant of an enemy, even if the enemy normally can't be a champion.
  • Added in RepentanceStitches Stitches: On use, fires eight tears from Isaac's original location. The tears synergize with Isaac's tear effects.


  • Added in RepentanceBlood Puppy Blood Puppy: Only increases the damage and size while it isn't hostile.
  • Added in AfterbirthEvil Eye Evil Eye: The eyes are not treated as familiars and therefore will not synergize with BFFS!
  • Guillotine Guillotine/Scissors Scissors: Doesn't change the head's size, but still improves its damage.
  • Added in RepentanceHive Mind Hive Mind: Does not stack.
  • Added in Afterbirth †Shade Shade: Retains the increased damage even after being absorbed.

No Effect[]

The following familiars will appear larger, but gain no actual benefits.

In-game Footage[]