Twelve years ago, after failing to save the crystal empire from King Sombra, Twilight Sparkle lost a great many things, her sister in law, two of her closest friends and even her number one assistant. Searching for revenge, Twilight learned of a spell that once used, absorbs the magic and soul of the being used upon. Using this on Sombra she corrupted herself and soon absorbed Celestia and Luna, turning her into one of the most powerful beings in the land. With this new power, quickly took over Equestria, and all of the surrounding nations.

Now at the head of an entire Empire, Twilight Sparkle received word of a new area of land , ten times the size of their entire continent. a land named, Esperimose. With this knowledge she and her armies set of to this new land in order to conquer it, however, a darkness long thought destroyed by the ponies of Esperimose has been gathering power, and with the arrival of Equestrian forces, the land of Esperimose will become the final battleground for not just the fate of Equestria and Esperimose, but the entire world.

Disclaimer
I do not own any already existing names or locations in this story, they are property of Hasbro.