Shortly after Twilight and Fluttershy get back from dealing with the feud between the Hoofields and McColts, the Mane Six and Discord deal with Discord II, now named Chaotix, when he conjures up a powerful force field around Canterlot that traps even Celestia and Luna and also starts levitating the mountain Canterlot rest on, set to drop said mountain right on Ponyville after the mountain reaches thirty miles in the air. While the Mane Six pit their Rainbow Power against Chaotix, Discord tries to save both Canterlot and Ponyville
I think this is a reference to Majora's Mask.