While exploring one of the catacombs beneath canterlot during a visit to her aunt's palace, Princess Flurry Heart is attacked by a horrifying creature the likes of which equestria has never seen. Confronted with such a terrifying monster there is only one thing for a young filly like herself to do...

Beg her parents to let her keep it.

Set between Ending of the End and The Last Problem.

Six powerful entities have awakened, being that are even more ancient than Equestria itself. When these beings threaten not only Ponyville but all of Equestria it's up to the Elements of harmony to stop them!
Unfortunately, they have no idea how, but one family has passed down the legends of this threat with each generation, and they alone know the secret of defeating them.
The last remaining member of the family: Derpy Hooves!