The Unnameable God

The Yuan-ti in Mystwall seem to be worshipping a dark god and are interested in the writs. The snake like cultists spoke of a dark god that has no name.

• The characters met the Yuan-ti in Mystwall in a snake's den.
• The characters saw a Dark Cleric who dropped off The Black Writ Questline.
• The party killed a Yuan-ti female known only as The Mistress.
• Yuan-ti are usually worshipers of demons, but this group seems to be part of the Cult of the Nameless One.

Learn more about the unnamed god.
Sulvaugren was attempting to bring back an aspect of the The Unnameable God by giving him the avatar known as the The Risen King.
Defeat Sulvagren and stop the Sacrament
Find a new way to destory the writs.
Use the item creation in Castle Sethius