Here is the authors description of the story

Rip in space has opened in the skies above the Everfree, and something powerful has fallen through. The entire forest has been petrified by unknown magic, and the entity responsible—only seen by a few—now appears to be hiding within its garden of dead trees and monstrous statues.

With the town of Ponyville put on lockdown, and concerns of an escaped prisoner from Tartarus worrying the surrounding lands, the Elements of Harmony now rally with the Pillars of Equestria to locate and quell these threats. Little do they know they are not the only ones scouring the woods for the source of this deadly, foreign magic.

Faced with certain peril, the heroes of Equestria must save their land by stopping a match made in Tartarus: the villain, Tirek, who seeks to drain all Equestria of magic, and this avian threat, which holds the power to drain life from anything organic.