The Ebon Triad was founded by Lashonna, a vampiric silver dragon, and Mahuudril, an avolakia envoy from the Wormcrawl Fissure, in the Well of Triptych Knowledge, a dungeon complex under a sickhouse known as Sinner's Sanctum in the city of Alhaster.
Lashonna and Mahuudril succeeded beyond their expectations with the cult, and today, the Ebon Triad is a self-sustaining organization that truly believes in its goal to unite Erythnul, Hextor, and Vecna into a supreme overdeity.