Candlekeep Mysteries/Xanthoria

"Xanthoria" is a short adventure module for 16–level players, collected in the anthology Candlekeep Mysteries, where players must stop a deadly plague by defeating a mad lichen lich.

Synopsis
In 1492 DR, a deadly plague is ravaging the Sword Coast. A group of adventurers travel to Candlekeep to research a way to stop it, and find the tome Xanthoria. The adventurers must travel to the Lykortha Expanse to deal with the creator of the plague, an insane druid who has undergone a horrible transformation.