The black mushroom is a quest item in The Golem and Shadow of the Storm quests. They are found ruins beneath Uzer. When used with a pestle and mortar and a vial in the inventory, black mushroom ink is made, which is used to dye several items black: Silverlight into Darklight, desert robe into black desert robe, desert shirt into black desert shirt, origami balloons, and blue wizard robe into black robe.
When eaten, it has no effects and heal no Hitpoints, but the player will receive the message "Eugh! It tastes horrible, and stains your fingers black." to indicate its intended use as dye.
- The name, shape, and properties of this fungi are a reference to real-world ink cap mushrooms, Coprinopsis atramentaria, which were historically used for ink or dye. They also tend to be inedible, though not particularly harmful.