A cult of Vecna
This is just one of many cults of Vecna, but it is the only one the Irregulars have encountered so far. One of its members, Veltargo, hatched a plan to steal and open a magically locked book stored in the Great Library of Founder’s Reach. The Irregulars killed Veltargo, but he was apparently not the only prominent member of the cult. A couple months later another member, Lord Kolta, discovered a way to turn into a vampire without needing another vampire as a sire. However, the Irregulars once again thwarted the cults plans and killed Lord Kolta. It was evident from Lord Kolta‘s correspondence that he had sent the formula for his ritual to a superior, so the cult is likely still around and active. The Church of Vecna in Founder’s Reach disavows any knowledge of this cult, of course.