The Apostates are often known as evil priests or the priests of Evil. As Priests have their angel, so Apostates have their Baalzadeen or demon companion. The Apostate must learn control over the skills of Evileye and Necromancy at a young age. When they get older and much stronger, evil sees fit to allow them to control the powers of the great skill of Apostasy.
The events leading up to the creation of the class, and later the Guild and House, are found within the Blood Congregation article.