Have you ever seen a crash between two mechas at high speed?
Even at the reasonable speed of two hundred kilometers per hour for each mecha, they would be smashing against each other at four hundred kilometers per hour.
At approximately 60,000 Kilograms per mecha, the crash between the two mechas was roughly equivalent to being pressed by a mass weighing a BILLION kilograms!
And that was assuming the two mechas were standard medium mechas.
With the Terrasaur and the Demon Guard being MUCH heavier than that, it was no surprise that the Demon Guard mecha despite its powerful armor, blew up like a motorbike crashing into a tower of lego.
KABLAMM!!
The first demon mecha literally disintegrated just like that.
The largest piece of the mecha that flew off was a human body sized armor plate. Everything else was… gone.