Whore of Babylon

Whore of Babylon is a passive item.

Effect

Increases damage by 1.5 and speed by 0.3 while Isaac has half of a red heart or less.
On Eve, the item has the following extra effects:
- The item is activated at one red heart or less.
- Her damage multiplier increases from 0.75 to 1.0 when active.

The effect is removed after leaving a room with more than half a heart (more than one full heart for Eve).
The effect may not be immediately applied if Isaac has lost red hearts without taking damage; the effect will activate upon entering a new room.
The effect is always active for characters without heart containers, such as ??? and The Lost, though other characters can also lose their heart containers through devil deals or items like Guppy's Paw, Abaddon, or Health Down pill.
III - The Empress grants a similar effect to Whore of Babylon for the current room which does stack with Whore of Babylon.
- Stacking The Empress on Whore of Babylon either via multiple cards or multiple activations of Blank Card increases damage by the number of uses squared, e.g. +1.5 * 2 * 2 total damage bonus for using the card on top of activated Whore of Babylon.
Upon obtaining the Whore of Babylon effect, a popup displaying the text "What a horrible night to have a curse" appears on-screen. This can be disabled in the game options.
As Keeper cannot have half of a health coin, this item creates no effect on him.
If the player has acquired any, the effect will be applied at one half full Bone Heart.

The text that appears when this item is activated is a reference to Castlevania II: Simon's Quest. In the game, the text appears when the sun goes down.
The Whore of Babylon is an evil creature mentioned in the Book of Revelation.
This item is used in Challenge #4 (Darkness Falls).