My Little Pony: Friendship is Magic S09E01 - The Beginning of the End - Part 1

Princess Celestia and Princess Luna decide to retire and hand off the ruling of Equestria to Twilight Sparkle and her friends, which sends Twilight into a tailspin of self-doubt. Meanwhile, an ancient villain bands together a legion of nefarious characters to conquer all of Equestria, challenging Twilight Sparkle and the rest of the Mane 6 to step in and save the day.