Chronicles of Khaldun: Bread and Circuses
Laired in Thanatos on the 113rd layer of the Abyss, the Demon Prince of Undeath, Orcus, is one of the most potent demon lords. His plots have long pitted him against the Raven Queen, as he has long wished to usurp the mantle of death-god. Of course, his success is complicated by the fact that he is also constantly plotting against his fellow demon lords, primarily Demogorgon and Graz’zt (as all three wish to claim the title “Prince of Demons”).
Lazghul the Lich-Lord is a known worshiper of Orcus according to the Raven Queen.