After they lost their home planet Cybertron to a devastating civil war, the Autobots and Decepticons arrive in Canterlot City, just as the Friendship Games came to their climactic conclusion, with Sunset Shimmer helping the human world's Twilight Sparkle overcome her dark alter-ego, Midnight Sparkle.

Sunset Shimmer and friends are drawn into the war when it reaches their city and, coupled with Twilight recovering from her ordeal, shocking revelations and new magical threats emerging from a familiar foe, the girls are in for an adventure that will change their lives forever...

Peace has returned to Canterlot High School and nobody fears Sunset Shimmer since the Battle of The Bands, but a new threat know as Decepticons, lead by Megatron, wants to conquer Earth and the rest of the Universe. Now Twilight Sparkle and the Rainbooms must join with Optimus Prime and the Autobots in their galatic civil war that last eons. Will the heroic Autobots prevail and bring peace to the Universe or will the evil Decepticons win this war and conquer Humankind?