Punny, but quite literal too @Scarifar
I was looking to create a demigod of madness. (working name is Pelegath) He would be a chaotic demigod not by choice but by nature and be as likely to help guardians of order as he would aid vanguards of destruction. A completely unpredictable entity who would enjoy screwing with sentient races just because he feels like it. He would the power to induce all manner of madness from garden-variety paranoia to full blown insanity. What damage he might cause would be entirely random and impossible to find a pattern in because the Mad Demigod would himself be mad.
I also have (what I think are) some really great ideas about how a demigod such as him could have stationary holy states and even gain a sizable amount of followers if you're interested.