The Birth of Harmony Twivine
As Equestria's fate seals slowly. Twivine meets the Mane 5, Starlight Glimmer, and Delta Brony and tells them that Lady Tirek has taken the magic from Twilight Sparkle, Celestia, Luna and Cadance. She also confessed that she released the power of Lord Tirek from her bonds to create Lady Tirek. Delta Brony realized that this was Twivine's predictions were true the whole time.
Princess Twivine Sparkle has a plan on defeating Lady Tirek and getting everypony's magic back in Equestria. So she decides to have Pinkie Pie, Fluttershy, Rainbow Dash, Rarity, and Applejack transfer their magic to her. It may be risky, but Prince Delta realizes that Twivine may be the key, because she is a part of Twilight thanks to the Mirror Pool, and she might have sum of the Element of Magic.
The ponies agreed to transfer their magic to Twivine. As a result, she becomes Harmony Twivine. Not only that, she has her Rainbow Power from the last time she faced Twilight. Now she is ready to face Lady Tirek and save Equestria.
One more thing, she's doing it the Star Fox way, so she'll fight alone to protect Twilight's friends.