Box of Friends is an unlockable activated item added in Afterbirth.
Effect
- Upon use, it adds one copy of each of Isaac's familiars for the duration of the current room.
- If Isaac has no familiars, a
Demon Baby will spawn for the duration of the current room.
Notes
- Lilith starts with this item by default, even if it hasn't been unlocked yet.
- If Isaac has more than one copy of the same familiar, it will still only add one copy.
- Blue Flies, Blue Spiders, and orbitals (Halo of Flies, Leprosy, etc) are not copied.
- Many familiars can be spawned in Greed Mode and Boss Rush, as completing waves charges the item.
Interactions
- 1up! / Dead Cat: Familiars are multiplied but do not give Isaac additional lives.
- Abel/Dead Bird/Eve's Bird Foot/Isaac's Heart / Isaac's Head / ???'s Soul / Milk!: These familiars are not copied.
- In the case of Milk!, the familiar itself doesn't appear, but instead it decreases tear delay by 2 (effective tears up) when used, without needing to take damage.
- In the case of
- Best Bud: If used before taking damage, the white fly will circle around Isaac. However, multiple white flies cannot be spawned, so using Box of Friends after taking damage or using it multiple times in a room has no effect.
- Bumbo: Will spawn a level 1 Bumbo regardless of the original Bumbo's current level.
- Pickup generating familiars: The copied familiars will drop pickups independently.
- Guillotine: Duplicates the Head circling around Isaac's body. Only one head will shoot tears.
- Key Piece 1 / Key Piece 2: Key pieces are multiplied, but do not complete the other half.
Synergies
- Acid Baby: Two or more pills will spawn where applicable.
- Bob's Brain: Adds an additional brain. When used upon entering a room, Box of Friends eliminates the item delay, which allows Isaac to launch Bob's Brain immediately.
- Car Battery: Adds two copies of each familiar.
- Cube of Meat / Ball of Bandages: Upgrades the cube/ball for the current room. This can be used to easily unlock the Super Meat Boy and Bandage Girl achievements.
- Daddy Longlegs: Familiar will be copied.
- Incubus: Creates additional Incubus familiars, which share the same tear modifiers as the player.
- Multidimensional Baby: Each copy of Multidimensional Baby follows the previous copy with a 2.5 second delay.
- Smart Fly: Very useful on Greed mode, as each usage will add an attacking fly, killing enemies and bosses very quickly.
In-game Footage
Trivia
- The Box of Friends seems to resemble the Lament Configuration of the Lemarchand's box from Clive Barker's Hellraiser.
- Might be a very obscure reference to a Yu-Gi-Oh! card with the same name.
- This item used to have a recharge time of 2, until an update on November 4, 2015.
- When playing in Korean, this item still has a recharge time of 2.
- In the game files this item's sprite is called "Pandora's Box" by a mistake.
Seeds
Switch 
WL8W DS4S (First Golden Treasure Room)
 The Binding of Isaac: Rebirth
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