Bad guys for my game?  I've got a dozen ideas.  These two are my favorites so far:

#1. The Ghost in the Machine
This one started out as a fairly mundane thing.  A wizard who came into his powers late had real trouble dealing with the magic-makes-tech-go-screwy aspect of his existence, as he was a total technophile prior to his discovery.  After his apprenticeship, he bends all thought to getting around this problem, and eventually hits the solution.  He takes himself on a nice long journey through the Nevernever, and finally hits the place where old technology goes to die.  There, he made contact with a . . . something . . . that didn't want to go quietly into that long night, and cut a deal with him to stay relevant.  So empowered with great technological hoodoo, said wizard returns and starts breaking the technology that made his cthonic master obsolete.  I'm thinking said technology should be something important, like, say, automobiles.  Or telecommunications satellites.

#2. The Death of Fire
The old gods have decided to press issues.  Prometheus stole the Divine Fire from the gods, and now the gods want it back.  Electricity stops working.  Fire follows soon after.  Only magic can conjure fire, and that makes wizards popular real fast.  The White Council flips out, snapped fairly neatly down the middle between 'We could be as messiahs to these people!' and 'Let's help them help themselves, shall we?'  Only hope is a long quest into the Nevernever to get the Divine Fire back.