Little Bear's Adventures of My Little Pony: Friendship is Magic - Twilight's Kingdom

Little Bear's Adventures of My Little Pony: Friendship is Magic - Twilight's Kingdom is another upcoming Little Bear/MLP:FIM crossover to be made by Hiatt Grey.

Plot
Twilight and her best friends travel to the Crystal Empire, where Twilight, in her role as a princess, is to help greet delegates from another nation. She finds this duty unfulfilling, and laments this to Celestia, Luna, and Cadance, unsure what her role in Equestria is. The other three assure her that her responsibilities will become clear in time.

Celestia has a vision revealing that a centaur named Tirek has escaped from Tartarus (due to events from the episode "It's About Time") and is now draining ponies of their magic. Gathering the other princesses, Celestia explains how they had stopped Tirek before and must stop him now before he becomes too powerful. Twilight is eager to help, but Celestia instead puts Discord in charge due to his ability to sense magical imbalances caused by Tirek's activity. Twilight returns home to Ponyville, disappointed at being unable to help, and heads for the ancient castle in the Everfree Forest to catch up on studying. Discord interrupts them and teases them about his mission, but makes sure to remind them of the locked chest at the base of the Tree of Harmony (from "Princess Twilight Sparkle"). Twilight suspects there may be something to help against Tirek inside, and she and her friends search the books in the castle. Twilight realizes Discord mentioned their shared journal, and finds stories written by the other five where they were challenged in regards to their core Element of Harmony, and were able to help another, receiving an item in return. They gather these items, which transform into five of the six keys needed to open the box, but Twilight realizes that she has not yet faced a challenge similar to theirs and thus cannot provide the last key.

Discord encounters Tirek, but he teases him with having freedom over friendship, so Discord decides to join Tirek as his chief henchman and thus, reverts to his old ways. Twilight is summoned back to Canterlot, where Celestia reveals Discord's treachery and that Tirek now has his sights set on taking the princesses' alicorn magic for himself.

Celestia reveals that the best plan to prevent Tirek from getting the alicorn magic is to hide it away within Twilight since her recent ascension to Princess is still unknown to Tirek. They transfer their powers to Twilight, who has difficulty in controlling the amount of power and avoids her best friends on returning to Ponyville while she practices control.

Tirek confronts the princesses and finds their magic gone. Despite this setback, he mocks that their plan is unable to change anything and banishes the three to Tartarus. He then expresses his gratitude for Discord's assistance by giving him a medallion as a sign of loyalty. As they discuss this, Tirek learns of Twilight's existence and sets off to Ponyville. With Discord's assistance, they trap Twilight's best friends and Tirek steals their power. He then turns on Discord and takes his magic as well, having only used Discord as a pawn to become powerful as he tells him he is no longer useful to him. Tirek finds Twilight and when she tries to run away, he destroys the Golden Oak Library in Ponyville. Enraged, Twilight attacks Tirek, and after a battle between the two superpowered beings, they realize they are evenly matched and Tirek offers to release Twilight's best friends in exchange for all the alicorn magic. Twilight comes to realize this is the same type of situation that her best friends had previously experienced and agrees to the deal on the condition that Discord is also freed. Tirek takes the alicorn magic and begins to go on a rampage.

Remorsefully, Discord apologizes for turning on them and gives Twilight the medallion Tirek had given him as a sign of his true friendship. Twilight recognizes this as the sixth key, and they quickly race to the box. With all six keys present, the box opens and powers the Tree of Harmony, causing Twilight and her best friends to be temporarily infused with a rainbow-like power. Together, they are able to face Tirek, repulse his attacks, and revert the magic drain. Tirek is weakened to his frail form and returned to Tartarus while Twilight and her best friends return the magic to all the other ponies in Equestria and free the princesses. The box is then sent by the Tree of Harmony into the ground at the edge of Ponyville, and grows into a tree-like castle. Celestia informs Twilight that it is now her new castle and she is now the Princess of Friendship with her responsibility to help spread friendship across Equestria with the help of her best friends, including Discord.

Trivia

 * Team Griffin/Eeveelution, The Griffin Family, Vinny Griffin, Glenn Quagmire, Cleveland Brown, Joe Swanson, Roger Smith, Bender Bending Rodríguez, and Minerva Mink guest star in this film.