Demon Heart

The Demon Heart is an Expert mode consumable item from the Treasure Bag dropped by the Wall of Flesh. It permanently gives the player a sixth accessory slot to use (while in an Expert mode world). This effect does not stack and may only be used once per player. While not in Expert mode, the slot will be disabled, removing the effect and appearance of any equipped item and preventing new items from being put into the slot, though an equipped accessory in this slot may still be removed.

Trivia

 * The Demon Heart is one of the few Expert mode items that cannot be equipped in any accessory or equipment slots, the others being the Bone Glove and the three parts needed to craft the Mechanical Cart.
 * It is also the only consumable Expert-exclusive item.