It's the red-tailed beasts!
There were 12 mechs, all different looking, fighting intensely against five red-tailed beasts. Bang bang bang! The sound of collisions never stopped. Whenever one of them crashed into the ground, it was enough to make the earth shake.
The red-tailed beasts were about the same size as the mechs, but they move more flexibly. Despite being outnumbered, they did not seem to be fighting at a disadvantage. The five red-tailed beasts evasively moved from building to building. The 12 mechs could not surround the creatures, and could only run around to keep them in sight.
Crash! Rumble! Dust was flying everywhere, as neither the red-tailed beasts nor the 12 mechs were particularly careful moving around the buildings. The red-tailed beasts were tough creatures, and the 12 mechs were also very strong. They chased each other around, destroying the buildings in their wake. Soon, all that was left was rubble.