Book of Revelations is an unlockable activated item.
The last book of the Christian Bible, donning a purple cover and a white cross etched on it.
Upon activation, Isaac gains a soul heart.
If The Book of Revelations is used at least once in a level, a Harbinger will replace the normal level boss. XL floors, however, are not affected by this and will spawn normal bosses. Harbingers may still show up of their own accord.
If the boss of the current level is a set boss (Mom, Mom's Heart, It Lives, Isaac, ???, or Satan) it will not be replaced. Similarly, if a Harbinger has already been fought in the current environment (e.g. if you activate the item in Basement 2 having fought Famine in Basement 1) the boss will also not be replaced.
Increases chances of a Devil Room to appear by 35%.
If used several times on one floor (like an XL floor) it may also replace the boss on that floor with a normal boss instead of a horseman.
- As with most activated items, items such as Habit, 9 Volt and The Battery decrease the charge time, increasing the effectiveness of this item.
- With both the 9 Volt and The Battery, The Book of Revelations can be triggered once for every room containing an enemy, provided the player waits for The Battery to activate at least twice before clearing the room. Because there is no upper limit on the number of Soul Hearts a player can carry, this can effectively add an additional Soul Heart pickup to every enemy-containing room.
- Having both Habit and The Wafer with this item will make the player invincible, as for every two hits (always only one half-heart due to The Wafer) the player takes in a room will fully charge this item, allowing it to be used to regain the lost health in the form of a Soul Heart.
- The Book of Revelations works particularly well with the XRay Vision-Secret Room-The Battery exploit, potentially providing a patient player with an arbitrarily large number of Soul Hearts.
- The Book of Revelation is the final book in the Bible, describing the eventual apocalypse and the 4 horsemen to usher it, which explains its secondary effect.
- The biblical book title is actually singular, not plural. It is shorthand for "The Revelation of (St.) John".