Bile lichen is a toxic, green-yellow substance resembling vomit. It flourishes where extreme heat and cold mingle, such as at the steam-vent openings to Icewind Dale's Underdark. One patch of bile lichen covers a 5-foot square.
If a patch of bile lichen is touched, it releases a cloud of spores that fills a 10-foot Cube and dissipates after 1d4 hours. When a creature enters the cloud for the first time on a turn or starts its turn there, the creature makes a DC 14 Constitution saving throw, taking 11 (2d10) Poison damage and contracting Lichen Plague on a failed save (see "Magical Contagions" later in this chapter). On a successful save, the creature takes half as much damage only.