Mysterious dimensional cracks started appearing around Ponyville and Canterlot to which Discord had no affiliation. Regardless, concerns were kept to a minimum and the sites were kept under control so ponies just ignored it and carried on with their everyday lives.

Meanwhile, Cheerilee had a special history lesson planned for her students. With the help of a fellow soldier and some books, the CMC learnt all about Ancient Chineigh, Neighpon, other western countries and their historical heroes.

After School, Applebloom went to visit the nearby lake, and she met the most interesting pony ever, who was supposedly dead through time back in Ancient Chineigh, now rejuvenated and awakened to fight once more.

From the mysterious mare, Applebloom learned about what happened to the Ancient Heroes and the dimensional cracks known as Chaos currently appearing in Equestria. The CMC, their Siblings and the Ancient heroes join forces and strive to investigate and seal these cracks once and for all.

This is a crossover towards the game Hero Busters by the game company Ucube. It's a mobile game that involves heroic figures from Ancient China (Liu Bei, Cao Cao, Zhuge Liang, etc.), Ancient Japan (Oda Nobunaga, Date Masamune, Sōji Okita, etc.) And from Western Lore (Achilles, Hercules, Julius Caesar, Leonidas, William Wallace, etc. Even Newton, Einstein, and Mona Lisa!).