All spells are cast on the caster.
Because magic spells fail, magic is widely and incorrectly understood to fail. But all magic spells work on the magician — and on the others in the circle, connected to the working. Parts of (because party to) the transformation.
A magical working is a fiction. (Reader-response!) Is ‘paracosm’ the right word? Ludocosm? Thaumatocosm? Ugh, maybe. It creates a space in which new practice is possible. This is why you wear a mask and practice improvisation: radical listening. Radically intense experience of that private fiction. The privacy it affords makes it possible to explore something deeply, to access impulses and inhabit personae.
The fictionality unthethers the context, the surroundings, from the binding consensus-reality — but also untethers your own actions and their effects. Within the fiction, magic can work. The spell is the fiction.
We keep two sets of books; we can live inside a fiction, many fictions. That’s what fiction is for. It begins with radical acceptance in the reader/listener/magician: agreeing to the premise, the provision, the proffer. Letting yourself be welcomed (answering the Campbellian call to adventure, with the final/ultimate adventure being living toward death). That’s the outset of the Errand, of course — choosing to set out, accepting limitation. Becoming foolish, becoming the Fool. You have to get humble (fuck around!) before you can find out.
All magic spells work on the magician. Which is to say: one way or another, they all work.