After the discovery of a portal beneath the Black Temple, the Alliance and Horde are locked in another bitter conflict to make use of the resources of the new world of Equestria. When the ponies of Equestria decide to accept the Alliance's offer of allegiance, their ancient rivals from the Griffin Empire ally themselves with the Horde. Tensions threaten to boil over into full-scale war for the first time in centuries, but little does either faction realize that far greater enemies loom on the horizon.