Last night, your buddy was thinking about calling one of those crazy psychic hotlines, he was really depressed, his girlfriend dumped him, and he wanted some good news. You know they’re all a scam, they give you some advice that could apply to everyone and a large bill to boot. You told him to go for it.
But now he’s missing. All you have is his cell phone, and something is wrong with it. You found it in your toilet today. Yeah, your toilet. It’s got all his old numbers and a few you don’t recognize. You tried to call some, but all you got was a what sounded like a bunch of voices muttering at once. What the hell is going on here?
Believable magic, like ordinary physicis, operates according to some invariable laws that always result in some kind of cost or "bounce back". The grater the magic, the more it should cost the character physically, emotionally, and spiritually.