Guromancy.

My name's not John, but why should I care what the entity called me. Maybe he didn't catch the notion that peole roll with John Doe for catch all reasons. Maybe it meant that, and knew full well but didn't want to learn the names of everyone who would recieve this gift. Wait, so there could be others...

I immediately glanced at a fly on the wall. At my whim it shifted in a floating mass of goo. I mentally demanded it inform me if it, other flies, and roaches were ever granted such powers, since I saw in its existence it had been around this before. No, it was gifted to me, by this same entity so that I could know more. But it instantly turned back into a fly, using counter magic to repel my attempts to gain information, proving all I needed to know.

Some roaches at least, as well as ant colonies and an occasional cat, often birds, were frequently humans in animal form. Sometimes a human pretended to be another human, tho I had already seen people could often pass as a stranger's close friends. This power would allow me to do more than skills could ever achieve

Shape shifting into a tank, or into a million bats, or into more matter and energy than currently exist within the observable universe? It was all possible now.

So I made my penis bigger. Not using this magic, but by watching porn and getting an erection. Before I put a finger to my member, I decided the mind control could be more useful for my personal tastes.

I contemplated using tentacles entangle some girls living together next door, or perhaps possessing them mentally so they'd do as I please. Most of all, shapeshifting them into monsters to torture each other hit a sweet spot for me, as I always loved the odea of seeing them embarrassed, physically pained, and especially horrified.