On Amonkhet, this would be the cataclysmic destruction brought on by a megalomaniacal dragon with aspirations to tyrannical deification. On Ravnica, this is…bad weather.
I’m having a hard time believing that the inhabitants of the city of Ravnica haven’t just died out. Why would anyone with a lick of common sense choose to remain in a place like this? Ravnica is the dumbest plane.