It saddens me every time someone has to ask about changing into something you are not. Do not I repeat do not practice fantasy spells or drink "potions" that change you into something i.e. fairy. Most likely it will do more harm.
Think, you are a human. All humans have the ability to wield magick. Yet, most don't because over half of the world is ignorant or skeptical to this art. You are here because you were either curious or wanted to further expand your knowledge. And by believing into something so... so impossible is stopping any knowledge that is true.
I want someone to pin this because questioning weather fantasy spells work or not is just dumb.
Thanks to everyone that answers with facts.
It's okay to dream, to image being an animal or creature, but we must all eventually realize that they are only dreams.
Key word; fantasy.
I'm sorry if I crushed your hopes and dreams but its time for a wake up call.
But in case you must be forgiven, there's the art of sculpting your own spirit, and because they are purely of magick they could be "shaped" into something fake. And because we don't really know what a demon or angle looks like, heck, they could appear or chose the form of a fantasy creature. But that's only a thought.