General:
* Devastation: Complete destruction; a state of ruin or desolation.
* Ruination: The state of being ruined; complete destruction.
* Havoc: Widespread destruction and disorder.
* Annihilation: Complete destruction or obliteration.
* Desolation: A state of complete emptiness or destruction.
More specific:
* Carnage: Great slaughter or bloodshed.
* Massacre: The indiscriminate killing of a large number of people.
* Scourge: Something that causes great suffering or destruction.
* Catastrophe: A sudden and disastrous event.
* Pandemonium: A wild and noisy uproar; a state of extreme confusion and disorder.
The best word to use will depend on the specific context and the type of destruction you want to convey.