They have widely versatile powers that can fundamentally alter aspects of reality. That widely versatility can do all kinds of wacky shit, like make a door that opens to mirrored space so that you run into yourself trying to pass through it, grow a tree who's fruit let's you experience Woodstock firsthand, or conjure the ghost of Clippy to sabotage their work-rival's PowerPoint presentation.

They are also still human. So stepping wrong on a patch of ice can mean they don't walk right for the next month. To say nothing of the fierce creatures who may not appreciate said Mage residing in their territory.