. . . "Years later, the Crystal Empire reappears in Equestria's Arctic North, bringing the evil King Sombra with it. According to the Applejack of this timeline, Sombra then retakes control of the Empire and wages war on the rest of Equestria, using mind control helmets to force the Crystal Ponies into his army of soldiers. Over the course of the next several months, the Crystal Empire's borders expand across Equestria, including the San Palomino Desert, the Badlands, and portions of Griffonstone."@en . . "Great Crystal War"@en . . "Years later, the Crystal Empire reappears in Equestria's Arctic North, bringing the evil King Sombra with it. According to the Applejack of this timeline, Sombra then retakes control of the Empire and wages war on the rest of Equestria, using mind control helmets to force the Crystal Ponies into his army of soldiers. Over the course of the next several months, the Crystal Empire's borders expand across Equestria, including the San Palomino Desert, the Badlands, and portions of Griffonstone. Princess Celestia and her subjects fight back against the invading Crystal Empire. The royal guards, Wonderbolts, and other ponies are enlisted into Celestia's army, serving as either soldiers or war effort supporters. Meanwhile, Princess Celestia's research mages look for a counterspell for Sombra's mind control helmets. The Twilight Sparkle and Spike of the series' main timeline briefly visit this reality and bear witness to the effects that the Great Crystal War has had on Equestria. They depart from this timeline before the war's resolution."@en . .