Telekinesis could be the single most OP spell there is. I know what you're thinking. "But there's tons of other spells out there. How can this be?"

Well when Twilight picks up the Ursa Minor what's stopping her from ripping a tree from the forest and using said tree as a baseball bat or something, and who needs offensive spells when you can launch a small object at high speeds or just crush someone under a boulder. You can also fly by floating yourself and maybe if your telekinesis became powerful enough you could turn Canterlot into a giant mace.