Well the first thing is that "fantasy" means make-believe. In other words, no fantasy spell will ever work.
Secondly, there are no spells that will turn you into a werewolf as they don't physically exist either. The idea of werewolves comes from medieval misunderstanding about several different medical conditions. And today they are entirely the product of fantasy novels and Hollywood films.
So while you may have written a spell it isn't going to work. Perhaps you might want to try writing a spell on something that could work such as protection, healing, money, job, etc.