Chaos follower throws moons at a planet to destroy mountains and cities

"A small meteorite struck the hive less than a thousand metres from his position. It hit with the force of a Deathstrike missile. Midway between the surface and the clouds, Profundis screamed. The fireball blossomed for hundreds of metres. Entire districts vaporised. The structural integrity of most of the upper reaches collapsed. Towers dropped like felled trees. Their mass shattered the habs below. The chain reaction built. An avalanche of millions of tonnes of rockcrete followed the Blood Disciples down. Khevrak yelled in triumph. Mountains were falling in their wake.

...A moon several kilometres wide hit the ocean south of the equator, within sight of the coastal city of Penitence. The city did not tower like Profundis. It spread its hundreds of millions over a region a thousand kilometres on a side. The blast hit with a wind of seven thousand kilometres per hour. It leveled all the spires. Ten million inhabitants died in an instant." - Lemartes