Book of the Dead

Book of the Dead is an unlockable activated item added in The Binding of Isaac: Afterbirth † (Booster Pack #5).

Effects

When used, spawns one of the following for each enemy already killed in the current room (capped at 8):
- 80% chance for an orbital bone familiar.
- 20% chance for a friendly bone monster.
  - 66% chance for a Bony.
  - 33% chance for a Black Bony.
When used, spawns one of the following for each enemy already killed in the current room (capped at 8):
- 80% chance for an orbital bone familiar.
- 20% chance for a friendly bone monster.
  - The bone monster starts as a Bony.
  - The Bony has a 25% chance to become a Black Bony.
  - The Bony or Black Bony has a 25% chance to become a Big Bony if a killed enemy has enough HP to meet the formula:
    baseHP + floor * stageHP * min(floor, 10) * 0.8^[1] > 18 + floor * 3 * min(floor, 10) * 0.8^[1]
  - The Bony, Black Bony, or Big Bony has a 25% chance to become a Bone Fly.
  - The Bony, Black Bony, Big Bony, or Bone Fly has a 1% chance to become a Revenant.
  - There is an additional 8.33% chance for the bone monster to become a Revenant on Mausoleum / Gehenna / Sheol / Dark Room.
Spawning an enemy other than a Bony/Black Bony is only possible after dying at least once to said enemy on the save file.
This item belongs to the Bookworm set. Collecting three items from this set will transform Isaac into Bookworm.

Notes

This item has a 1% chance to drop when defeating The Forsaken.
Orbital bones deal contact damage equal to Isaac's damage at the time it was spawned and repel enemies that touch them.
- They block 3 shots or deal 2 ticks of contact damage before being destroyed.
- They block 1 shot or deal 2 ticks of contact damage before being destroyed.
Bonies deal 5 contact damage and 5 damage with thrown bones.
Bonies deal 8.7 contact damage and 6 damage with thrown bones.
Black Bonies will explode on death, dealing 40 damage to enemies it hits. The explosion will not hurt Isaac. It will knock him back.
Internally, the Book tracks up to 32 positions each enemy was killed at in the current room, and uses those locations as spawn points for bone orbitals and Bonies.
- Using the book will always spawn at least 1, gives the rest a 66% chance for each location to spawn one, and can spawn up to 8 per use.
  - Having more locations than 8 will effectively increase the odds to spawn each.
  - If one of these locations doesn't spawn a bone orbital or Bony, it can still spawn one if the book is used in the same room without leaving. However, once a location spawns something, it cannot do so again.
Using the book in a room that had no enemies or was re-entered does nothing and expends the charge.
Orbital bones occupy the same area around Isaac as Blue Flies, meaning Isaac can have an incredibly dense ring of bone orbitals around him that nullifies most attacks.
Friendly monsters killed in the current room can also be used by Book of the Dead.
Destroying Black Poop will damage the friendly monsters acquired from this item.
Frozen enemies (enemies killed by Uranus, Cube Baby, etc.) will not summon bone familiars unless their frozen bodies are shattered.

Synergies

Book of Virtues: Spawns tiny skull wisps on the inner ring. The wisps fire bones and spawn friendly Bonies when destroyed. The book will summon wisps regardless of whether or not there were enemies killed in the current room.
Car Battery: Gives a higher chance to spawn bone orbitals or friendly enemies, and can spawn up to 16 per use.

Interactions

Ace Cards: Friendly monsters are still affected by Ace Cards and enemies that are turned into pickups can't be animated.
Baby-Bender: No effect.
Blood Puppy: Either angry version of Blood Puppy will target friendly enemies as well and can drag them along with it when it charges them. Blood Puppy cannot damage friendly enemies however friendly enemies can damage Blood Puppy despite not targeting it outright.
Broken Modem: Broken Modem also affects friendly enemies and projectiles created by them.
Contagion: Poison effect can spread to and kill friendly Bonies.
E. Coli / Flush!: Enemies that are turned into poop can't be animated.
Eraser: Bonies erased via Eraser will never spawn again from Book of the Dead, greatly decreasing its power.
Ghost Bombs / Hungry Soul / Purgatory / Vade Retro: Explosions from ghosts can and will kill Bonies.
Glowing Hourglass: Each use of Glowing Hourglass that does not move Isaac to a different room than the one he is currently in (such as the starting room of a new floor) will duplicate friendly enemies and orbital bones. (This is possibly a bug)

In-game Footage

Unlockable Achievements

Mystery Egg - Spawn three charmed enemies in the same room.

Gallery

Concept art for "Reanimate" (misspelled as "Reanimte"), an early version of Book of the Dead, on the right side along with other Booster Pack items and trinkets, by Edmund McMillen.

Trivia

The Book of the Dead is a collection of ancient Egyptian funerary texts made out of papyrus, consisting of magic spells intended to assist a soul's journey through the Duat (underworld) and into the afterlife.
The quote "Rise from the Grave" is a reference to the beginning screen of the video game Altered Beast.
This item's effect may be a reference to the book of the dead from NetHack, which also summons multiple undead monsters around you.

Bugs

Bug!	If sufficiently many bone orbitals are created, other familiars may disappear. Collecting a new familiar or resuming the run will restore the missing familiars.