Door

Door is a consumable.

Source
Doors can be crafted in the level 1 Sawmill with the following components:
 * 2x Board

Usage
A Door can be used on a floor inside a mine or a dungeon to create a door to the previous and / or the next dungeon level. The door allows the player to freely travel between the levels and does not disappear after the player exits the dungeon.

Doors can be placed strategically to allow the player to descend to a boss room, treasure chest, or a flock of Fireflies quickly.