unprophesied_of_ages

"There's a god of Ruin, which was mostly imprisoned by the slightly less powerful god of Preservation at the cost of its own mind. The prison needs to be remade every thousand-and-a-bit years—Preservation conveniently left power lying around for this when its mind died—or else Ruin breaks free. And if the person who does the imprisoning makes any mistakes at all, they risk accidentally killing everybody with their new omnipotence. I very nearly did that myself last time.

So while I like my world, I'd prefer one that doesn't have a recurring single point of failure."