The country of Marence is on the route to conquest, and after allieing with Gryphony, turns it's eyes to Equestria. At the same time, a mysterious young Alicorn shows up from nowhere, and seems to terrify all the wild life. Nopony knows why, though. The Mane 6 and all their friends are needed on the front lines. But what is the new Alicorn's agenda?