If you destroyed a modern city in your setting, how would you do it?

Far as I can tell, the Moon hitting the Earth at all, in any way, would lead to The End of the World as We Know It—class 4 or 5, at least. But I don't think the earlier poster was referring to the Moon falling.

Yeah, the moon thing wasn't me Tom.

I just went for the unimaginative "(magic) big explosion." Thinking about the damage it did, it was probably bigger than a nuke (but with no radiation).

^ Oh, my bad. 400,000 might be a realistic estimate if the town/city was on the smaller end. The largest deliverable nuclear weapons would entail 1,000,000+ killed/wounded in large cities depending on time of day and a couple of other factors.

On an unimaginative note, I have a Naruto fanfic in which Naruto knows a version of bunshin daibakuha (exploding clone) that can, if you're feeling suicidal, be used by the original as well. If he dumped all his chakra and the Kyuubi's into that...well, I'm not sure of the likely magnitude, but a clone with a tiny fraction of his own chakra and not even using it all for the technique can gouge huge craters in stone.

Most of my cities have been depopulated by plague. If I wanted to physically destroy on I'd rely on mother nature. Tornados and/or wildfires would do nicely.

Most of my cities are destroyed via low-end weapons. The use of combat ground troops in a city quickly reducing it to rubble without big explosions or the like. Instead it's more the use of mass rockets, rail guns, lasers defence drones and hypersonic deployments.

I would kill off all the trash collectors and sanitation workers and let the filth and pestilence kill everyone.