The war between the two sisters have been going on for months, Pony's fighting each other, the Solar Empire was being attacked by the Lunar Republic and Celestia had to do something before her kingdom is destroyed. Princess Twilight and Princess Celestia have been hiding in a secret place for days. The rest of the ponies where in underground tunnels to shield them from the war above. Nightmare Moon has sent a letter to the two princess stating that Celestia must meet Nightmare Moon at the abandoned Colosseum on the other side of the canterlot mountains, Celestia agrees but does not tell Twilight about the upcoming events.