BFFS! is a passive item.
Effects[ | ]
- 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 which is unaffected.
- Some familiars have unique synergies.
- Doubles the damage of Familiars that deal damage through tears and contact damage.
Notes[ | ]
- 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 are also affected by BFFS!.
- Wisps are also affected by BFFS!.
- Blue Flies and Blue Spiders are not affected, they instead benefit from Hive Mind.
- Does not increase the frequency or effectiveness of Status Effects applied by familiars.
Wisps are also affected by BFFS!.
Synergies[ | ]
- BBF/Bob's Brain: Doubles impact damage and increases explosive damage by 25.
- 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.
- Blood Oath: Adds 2 extra full hearts worth of bonuses if any health is drained.
- Holy Water: Double water damage and spawns a blue flame at point of impact.
- Incubus: Shoots tears that do 2x Isaac's damage 1.5x Isaac's damage. Still deals 2x as Lilith.
- 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: Spawns an extra Blue Spider.
- Lil Spewer: Increases the creep pool's size, but not its damage.
- Lost Soul: Gives the Lost Soul a Holy Mantle effect.
- Mystery Egg: Spawns a champion variant of an enemy, even if the enemy normally can't be a champion.
- Stitches: On use, fires eight tears from Isaac's original location. The tears synergize with Isaac's tear effects.
- Succubus: The aura's radius increases, but the damage multiplier and damage to enemies remain the same.
2x Isaac's damage 
Interactions[ | ]
- Blood Puppy: Only increases the damage and size while it isn't hostile.
- Evil Eye: The eyes are not treated as familiars and therefore will not synergize with BFFS!
- Guillotine/Scissors: Doesn't change the head's size, but still improves its damage.
- Hive Mind: Does not stack.
- Shade: Retains the increased damage even after being absorbed.
No Effect[ | ]
The following familiars will appear larger, but gain no actual benefits.
- 1up!
- Angelic Prism
- Brown Nugget
- Censer
- Dark Bum
- Dead Cat
- Depression
- Dry Baby
- Farting Baby
- GB Bug
- Hallowed Ground
- Headless Baby
- Holy Water
- Isaac's Heart
- Key Piece 1
- Key Piece 2
- King Baby
- Milk!
- Multidimensional Baby
- Paschal Candle
- Punching Bag
- Rotten Baby
- Sissy Longlegs
- Slipped Rib
- Sprinkler
- Star of Bethlehem
- Trinity Shield
- Vanishing Twin
- YO LISTEN!
In-game Footage[ | ]
Trivia[ | ]
- BFF stands for Best Friends Forever.
- This item is used in The Family Man (challenge #19) and Scat Man (challenge #36).
 Familiar Modifiers
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| Items |
| Trinkets |
 The Binding of Isaac: Rebirth
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