Twilight's Kingdom (Part 1) - (Part 2).Twilight's Kingdom (Part 1): Twilight Sparkle laments her unfulfilling duties as a princess, but Celestia, Luna and Cadance affirm that she will have a duty to serve. News arrives that Lord Tirek, a powerful centaur and one of Equestria's ancient enemies, has escaped from Tartarus and is draining magic from ponies to grow stronger. Celestia sends Discord to capture Tirek, to which Discord convinces Twilight and her friends to try opening the chest from the Tree of Harmony, which he believes contains a way to defeat Tirek. In reviewing their shared journal, Twilight discovers her friends have each been challenged over their respective Elements of Harmony and rewarded with a gift from someone they inspired. These gifts turn out to be five of the six keys needed to open the chest, but Twilight has yet to have a challenge herself. Meanwhile, Tirek convinces Discord to join forces with him and together they plunder more of Equestria's magic.
Twilight's Kingdom (Part 2): As Tirek continues to drain ponies' magic, the princesses give Twilight their own magic so as to hide it from Tirek, who is unaware of Twilight's existence. Tirek captures the other princesses and, learning of Twilight, turns towards Ponyville. There, he drains the power from Twilight's friends and betrays Discord by stealing his magic as well. Twilight faces off against Tirek in a destructive battle that ends in a draw. Tirek offers Twilight the freedom of her friends in exchange for her magic, to which she agrees by ordering Discord's release as well. Remorsefully, Discord gives her a medallion he had received from Tirek in mock alliance. The medallion becomes the final key needed for the chest. Twilight and her friends open the chest and it bestows them with a new power that allows them to reimprison Tirek, free the princesses and restore everypony's magic. The chest then transforms into a new castle for Twilight to reign alongside her friends as the Princess of Friendship.