During Waterdeep's Mintarn Initiative, the Waterdhavian nobles assigned Aeron Illiam and Vladimir Drulk in charge of maintaining the island. Drulk, with Illiam's funding, founded a magic college in Port Mintarn where he experimented with Lycanthropes, Necromancy, and a strange parasite. These combination of factors eventually led to humanoid test subjects.
These experiments led to the creation of The Rot, a dangerous ever-evolving disease that affects humanoid creatures. It turns their skin a saturated shade of grey while growing their teeth and fingers into fangs and claws. These creatures were later known as the Rot Walkers.