Foul Air
Circles: Death, Destruction
Description: Each turn, all units in the universe roll a fort save or take minor ability damage from poison fumes.
OK, this is crazy, end of the world, Armageddon type magic. People have said they wanted it. Well, here it is. It's going to have to be late game, high maintenance cost, etc. It can be dispelled, cities can be defended against it, etc. Anyways, it pretty much writes itself.
Thoughts?
Also, we might want to put this in Air, not Death.