The Book of Belial

Not to be confused with Satanic Bible.

The Book of Belial is an activated item.

Effects[]

Gives +2 damage for the current room.
Guarantees the Devil Room or Angel Room to spawn after killing a boss while holding it.
- Increases the chance to open the Devil Room or Angel Room by 12.5%.
This item belongs to the Bookworm set. Collecting three items from this set will transform Isaac into Bookworm.

Notes[]

Judas starts with this item by default.
The damage bonus does not stack with multiple uses in the same room or with XV - The Devil.
- Additional uses in the same room or combined with XV - The Devil give +1 damage per use.
While activated, switching items will end the bonus damage effect.
If the Schoolbag and a second activated item are held, the book must be equipped in the primary slot to receive the Devil Room / Angel Room bonus.
Only guarantees Devil/Angel Rooms on floors that they can normally appear on, and, unlike Goat Head, picking up The Book of Belial after killing the boss will not open the Devil/Angel Room door.

Synergies[]

Blood of the Martyr: Causes The Book of Belial to apply a 1.5x damage multiplier on top of its normal effect. This multiplier cannot stack with multipliers from Cricket's Head or Magic Mushroom.
Book of Virtues: Spawns black and red wisps in the middle ring. Wisps deal double damage compared to normal wisps.
Car Battery: Gives +3 damage for the current room.

Judas' Birthright Combinations[]

While holding Birthright with Judas or Dark Judas, Book of Belial is able to be held alongside another active item, similar to Book of Virtues. The book's damage bonus is equal to (2/3) * number of charges the overlaid item took to use. Items that do not require charges to use do not grant a damage bonus unless there is an exception listed below. Certain active items also gain additional special effects:

Alabaster Box: Changes the payout to 2 Black Hearts and 1 item from the Devil Room item pool. If a Devil Deal has been taken, the payout is boosted to 3 Black Hearts and 2 Devil items.
Bag of Crafting: Collecting Red Hearts, Half Red Hearts or Double Hearts with this item has a chance to transform them into Black Hearts. When a heart is transformed in this way, a special sound plays and a black smoke puff appears. Does not work with Scared Hearts.
Blood Rights: Invokes the effect of Razor Blade along with its original effect.
Book of Virtues: Can be stacked along with Book of Belial, allowing you to carry 2 passive books and an activated item on top of them.
Clicker: Replaces the most recently acquired item with Pentagram.
Damocles: Grants a permanent damage up.
Dark Arts: Allows gain of temporary damage ups when when using Dark Arts, similarly to Tainted Judas.
Decap Attack: While the head is detached from the body, grants a huge damage and tears up that breaks the tear cap.
Dull Razor: Essentially acts as a free damage up for the room.
Forget Me Now: Grants a damage up for the entirety of the new floor.
Genesis: Grants a free Pentagram that will not be removed by Genesis.
Glass Cannon: Activates Book of Belial when broken. The damage up persists until Glass Cannon is fixed.
Golden Razor: Damages every enemy in the room and applies the Midas' Touch effect on non-boss enemies, giving them a chance to drop coins on death. Damage dealt scales with Judas' damage.
Guppy's Paw: Grants a permanent 0.5 damage boost for every converted heart.
How to Jump: Leaves a trail of fire that deals 2 + 0.2 * floor contact damage and sets enemies on fire. The burn damage is equal to Judas' damage.
Isaac's Tears: Launched tears have boosted damage which scales with Judas' damage.
IV Bag: Activates Book of Belial with each use.
The Jar: Expends one heart from the jar at a time. Each heart used grants a damage up and creates a puddle of red creep that deals 2 damage per tick.
Jar of Wisps: Spawns Satanic Bible wisps that boost the chance to encounter a Devil Room.
Kamikaze!: Invokes the effect of The Necronomicon effect along with the original effect.
Magic Fingers: Has a chance to induce the effect of Golden Razor.
Magic Skin: Grants a permanent damage up upon each use. The damage is not lost if the broken hearts are removed.
Notched Axe: The axe receives a purplish glow and receives the following upgrades:
- Increased durability: each use of the axe has a very high chance not to use a charge.
- Faster usage: the axe can be swung faster.
- Higher knockback: enemies are knocked back when hit, receiving 8 + 0.2 * floor damage if they collide with a wall, obstacle, or other enemies.
- Fire effect: the axe will set enemies on fire. The burn damage is equal to Judas' damage.
- Increased luck: destroying obstacles with the axe has an increased chance to spawn pickups.
  - Destroying Poops will spawn pickups much more frequently. When combined with Petrified Poop, the chance becomes 100% and will often result in multiple pickups from a single poop.
  - Destroying Tinted Rocks will drop more consumables than usual, similarly to Super Special Rocks.
  - Destroying Urns has a higher chance to drop more coins. The coins can be of different variants, such as Dimes, Lucky Pennies, Golden Pennies, etc.
  - Destroying Mushrooms, Skulls and other alternative rock variants has an increased chance to drop their respective rewards.
  - Destroying Fool's Gold rocks will drop significantly more coins.
Pandora's Box: In addition to the item's expected reward, spawns one of the following demonic familiars: Blood Puppy, Dark Bum, Demon Baby, Incubus, Lil Abaddon, Lil Brimstone, Succubus and Twisted Pair.
Plan C: Respawns Judas as Dark Judas if he has an extra life.
Potato Peeler: Grants a much higher permanent damage up on each use.
Razor Blade: Invokes the effect of The Necronomicon effect along with the original effect.
Sacrificial Altar: Grants +10.8 temporary damage up for every sacrificed familiar. The damage bonus scales down to 0 over time, similarly to Red Stew. Sacrificing blue flies or blue spiders has no special effect.
Sharp Key: Invokes the effect of Razor Blade along with the original effect.
Stitches: Creates a shadowy line similar to Dark Arts between Judas and the familiar. Enemies caught in the line are damaged.
Urn of Souls: The stream of fire is replaced with a controllable Brimstone beam that deals more damage the longer it's active. The damage ranges from 2.5 to 3.1 and scales with each floor, reaching a range of 5.4 - 6.7 on Home. Souls dropped from enemies are colored red, and the Urn displays a red graphic on the HUD when active.
Vade Retro: Ghosts home in on enemies upon use, similarly to ghosts spawned by Purgatory. The ghosts deal 2x Judas' damage.
Wavy Cap: Grants an additional permanent damage up depending on the current amount of Wavy Cap usages. Clearing a room will decrease the total usages but will not remove the damage bonus. Wavy Cap will not grant additional damage bonuses unless the amount of times used exceeds the previous highest usage count.

In-game Footage[]

Gallery[]

Book of Belial when activated.
Unused image for use animation. This sprite is closer to the one used in the original game.
3DS The icon of the Book of Belial as seen on the lower 3DS screen.

Trivia[]

Can still open Angel Rooms even though it is a Satanic book.
It is one of the four books in the Satanic Bible.
Belial is a name used for Satan in some Jewish and Christian texts.
This item is used in Bloody Mary (Challenge #37).
The previously unused item ID 59 is now occupied by the active/passive version of Book of Belial, which is obtained when Judas or Dark Judas has Birthright.
- Despite this, this version of the item is not obtainable by other characters if you use Spindown Dice on an item pedestal of item ID 60, The Ladder, it'll skip to Book of Shadows.
The effect of Notched Axe with Judas' and Dark Judas' Birthright is a reference to Minecraft's enchanting mechanic.
- All of its upgrades are based on existing Minecraft enchantments - Unbreaking, Fire Aspect, Knockback, Efficiency and Fortune.