It was Pinkie Pie's idea. NOT Twilight's. Pinkie Pie and Twilight prank Celestia with a letter. Look out, Celestia!

Creatures of all kinds are attacking Equestria and the princesses's combined magic can only hold off so many attacks for so long. The Mane 6 must bring myth to life and find the legendary Star Knights in the unknown beyond Equestrian borders before Equestria falls. Meanwhile, Derpy discovers shocking secrets of her own. What she does with her newly-discovered, deep, dark secrets will decide the fate of Equestria's future. Could this be the end of Equestria? Will the Mane 6, Derpy Hooves, and Spike be able to save Equestria in time? Will the Star Knights join their side and help end the war in victory? Will Derpy make the right decision? This is only the beginning. There might be more power behind enemy lines than what is known...