First came Discord, then Nightmare Moon, then another showdown with Discord, finally after that came the Changelings! What was the true cause behind all of these attacks on Equestria? It all started in the past. A dark past that involves a Unicorn known as Shadestone who was a former apprentice of Princess Celestia! Because of the tragic events that have so far befallen Equestria, the Gates of Tartarus are slowly weakening and Shadestone's prison along with it. The Mane 6 must be prepared to challenge their greatest foe yet! Can friendship stop this formidable foe? Or is there no hope left at all?