Taking place in a world where the Mane 6 never were born. Starlight, Sunset Shimmer, Trixie represent the elements of harmony. Luna became Empress after destroying the rulers of the Planet of Equestria one by one. Starlight (Magic, Laughter) Sunset (Honesty, Loyalty) and Trixie (kindness, Generosity) go camping in the Everfree on a vacation in a slightly dystopia Equestria. A vacation that becomes a true horror as an ancient evil awakens.
You see, legend has it, a thousand years ago After Celestia fell, Luna fought an evil alicorn of love above the Everfree; burying her body within a circle of dead trees. As she died, she cursed the site of her demise so that if her name was spoken within it's hallowed grounds, she would rise once more.
But surely that's just a mare's tale...right?