Doomvault

The Doomvault was a large dungeon underneath Thay. It was a place where Arthindol imprisoned demons and the Chosen of several deities to fuel himself, making him a demigod.

Arthindol's plans were foiled when the party of Zero Uchiha, Rose, Annastasia Elizabeth Star Uchiha, and Lucien Lachance infiltrated the Doomvault with the help of Hamun Kost. They freed the demons and the Chosen, stripping Arthindol of his status as a demigod.

Even still, Arthindol was a powerful lich, and the party struggled to defeat him in his Phylactery Vault. Rose was killed, and her soul briefly trapped within Arthindol's staff. However, she was freed when Zero broke the orb at the head of the staff.

Myrja
The Red Wizard, serving Arthindol in unspecified experiments. She was quick to betray him, however, and made a plea to be spared by Zero and the party, which was accepted. She later fled the Doomvault once Arthindol was killed, and made her way to Phandalin.

Curran Corvalin
The Chosen of Tymora. He was free from his imprisonment by the party, and was teleported out of the Doomvault by Myrja. He eventually found his way to Phandalin, where he now serves as a priest of Tymora in the temple.

Lumalia
A deva in service to the goddess Mystra. She was turned into a statue for several years, but was freed by Zero and went on a Red Wizard-killing rampage.