Mega-Storm
The nuclear power plant, situated atop tall riverside cliffs some ten miles inland from the city, has seen many of the area's heroes in these trying times. Groups of heroes exhaust themselves rescuing people from homes not strong enough to face the extraordinary weather, repairing the power grid to keep the lights on in health care facilities, re-directing flooded rivers from the Orphanage for the Blind, or other endeavors to minimize the storm's damage. Once exhausted, some of the groups are allowed a slight respite guarding the power plant. The plant, itself, is fairly secure, even from the storm. This allows the heroes to refresh themselves before returning to the fray. Then, things change.
It starts out as almost imperceptible modulations in the noise and rhythm of the rainfall, so that it almost seems like the heroes can hear human laughter echoing about them. This will grow in diabolical intensity until there can be no doubt that there is, indeed, laughter coming from the storm, itself! Flashes of lightning reveal clouds that have taken on the look of a grim and mocking human face looking down upon them.
The river explodes from its banks, flooding the parking lot of the power plant. The workers, trapped in their cars, call for help. But when any one approaches, the river is back to where it began and the cars are empty. Old enemies appear nearby, flying about in the storm and attacking. As soon as they're approached, they vanish only to reappear farther away. It doesn't take long for everyone to realize that they're not all seeing the same thing!
The face in the stormclouds, which sometimes appears as an entire human body in a long, billowing cape, continues to laugh through it all. He says, "you pathetic worms. Nothing you do will slow my progress, and nothing you can do will save you."
The apparition ignores any attempt to communicate, and if the clouds making up the apparition are disturbed it reforms elsewhere.