Gregor was a member of the Cult of Dark One. The Heart Ritual was given to him for safe keeping. However, he went missing in the forest and ended up dead. He was buried and became a Wraith, the Master Wraith, his barrow haunted. Years later Paladin Pyotr searched for his barrow. However Gregor was too much for the paladin and killed him. Decades later the Hero discovered Gregor's barrow and finally defeated the creature once and for all (taking the Heart Ritual).