I read a book in the 80s about a young sorcerer that learns how to bind demons to rings. I'd love to re-read it and would appreciate some help identifying the book.
My recollection of the book: The story begins with "man" seducing and impregnating a witch/sorceress. She gives birth to a son. The young man eventually serves an apprenticeship under his mother's enemy, a sorcerer that knows how to bind demons to rings. A woman serving the master sorcerer secretly teaches the fledgling sorcerer the art of demon-ring creation and eventually reveals to the young sorcerer-in-training that "she" took on a male body and fathered him with the master sorcerer's seed. She introduces him to a variety of demons and some allow the young sorcerer to bind them to rings. Father and son eventually fight with bound demons and the son emerges victorious. The demon "father" retakes his original body and reunites with the witch/sorceress.