I would abuse some sort of time manipulation powers. I don't mean I'll go back in time and kill Hitler or something; I wouldn't want to mess with the past.
No, what I would do instead is befriend certain people, and when I figure out where they live, start messing with them. It'll start off with their keys being placed in the toilet, then it'll escalate to assemblying their car in their kitchen. It would escalate more and more til I got to the point of supergluing their furniture to the ceiling.
By the time they call the cops to explain that someone is messing with them/their home is possessed/etc, I would reconfigure everything back to it's normal appearance. Any photos they may have taken would be deleted.
Every person you've ever met that was batshit insane; you know how they got that way? Me. It would all be because of me.
