Schemes of the Lich King
A race of evil dwarves whose souls have turned black from the fell magic they practice. They seem to have a major encampment in the mountains near Moonwreck, feeling emboldened to attack the surface world only after the palace of Princess Argenta fell to evil forces.
Further, the Duergar seem to have a relationship with either the Lich King or the Diabolist. As servants, either knowingly or unknowingly, they have attempted to stop anyone from understanding the secrets of the Dark Tapestry.