Another disgusting deity of the Skandians, Hergel was one of the Vallas' appearances, and this god appeared as a vulture. He and the other two Vallas are toghether the gods of revenge, and Oberjarl Ragnak swore to them to avenge upon Duncan and his family after his son was killed in their country. If you swear to the Vallas, there is no turning back. Therefor, this is a very risky and uncommon thing to do.