Tomb of Horrors

From Syra D&D Wiki

The Tomb of Horrors, hidden in the mountains north of Silverstone, is an infamous destination for adventurers seeking glory, treasure, or evils to smite. While many have declared their intent to cleanse the Tomb of its evil, none have ever returned.

The Tomb was created by the demilich Acererak, a devotee of Nerull, and the entire dungeon functions as a massive altar to the god of death, and gains power from the souls of those who perish within. It was theorized that Acererak sought to use its power to become an exarch of Nerull, but with Nerull's death it is unknown what Acererak's current goals are.