SPOILERS
I've only watched one episode of season 3 of Riverdale but I have a whole theory.
#1 So in the last episode of CAOS, Miss Wardwell says they need one more thing for Sabrina to fullfill the prophecy. At first I thought it was the Greendale thirteen because she signed the Book of Beast, but I'm pretty sure we were never actually told the prophecy. What if the prophecy has something to do with the Gargoyle King.
#2 Madame Satan/ Miss Wardwell possessed Clifford Blossom to kill Jason. Since Clifford and Hal come from the same kin, she possessed Hal to become the Blackhood to balance it out
