A take on Humans Acting Villainously: Celestia has won, humanity and all they were has been consumed. But uneasy rests the tyrant's crown. The Newfoals remember things that go bump in the night, and now even Celestia must fear them.
Ortalians are the perfect soldiers, but do not hesitate to bolster their ranks with a wide array of mechanized units. Executioner-class mech is but one they employ to annihilate Empire's enemies. Then Discord happens and steals a mech.