The Werebear Bunch
Ergion, the Blessed
One of the Thirteen Heroes
Ergion was warped and twisted by the time he faced the party. Even so, he did not get a chance to demonstrate the extent of his corruption, being struck down before he could strike himself.
Once, Ergion Valesworn was one of the Thirteen Heroes of Faerun: an individual with such great power that he sealed the Demon Lords back into the Abyss. However, unlike the other heroes, who were sealed themselves into various weapons and items as a result of the seal backfiring, Ergion was struck with cowardice and fled from the scene. He became consumed with guilt, refusing to show his face again until he could be redeemed and going to extreme lengths to find such redemption (Including the abduction of an Elven woman). Ergion eventually resorted to sealing himself inside Leomund’s Magical Mansion, the former guild halls of the Thirteen Heroes, and saw to studying demons and devils to learn of their powers, in term becoming seduced and consumed by them.
When the Werebear Bunch came across the mansion (a supposed safehouse away from the chaos of Waterdeep) it had become appropriately warped by Ergion’s corrupt mind. They confronted Ergion in his unholy chapel and dispatched of him quickly, taking the mansion for themselves.