Morimbuul is the former daemon tutor of the Blood Congregation. He entered the Prime Material Plane in the year 318AF through a rift in his own plane. Unfortunately due to the interferance of a priest named Valeo and his angel, the rift was sealed before any more of Morimbuul's demonic brethren could pass through. Xerimor, who had opened the rift, bound Morimbuul to slavery and forced him to teach all he knew of the daemonic arts. This led to the founding of the Apostates guild which is now known as the Blood Congregation.
Over the years, Morimbuul has revealed himself to be a deceptive creature, he constantly schemes to escape his confines, and has on more than one occasion summoned red daemons to hassle the citizens of Mhaldor. He raped three high ranked Mhaldorian women, Tyn, Ladydeath and Ravai, and through them, respectively, had three half-demon offspring, Sabatu, Nebatu and Aznahz the Haruspex. Aznahz has since succeeded his father as tutor to the House, leaving the elder demon locked up in his prison without contact to the outside world.