Not A-Mused

When a fresh new museum turns up in Equestria, it's revealed to be enchanted and all-knowing about every one of the displays within. All history within Equestria's history is slowly being revealed, but this includes things best not known. This is especially useful for a returning Backgammon who wants to use this knowledge to become 'better than Twilight', stealing massive archives of events in history and eventually hog any hope of achievement left. When investigating stolen exhibits, the Mane Heroes and Lodgers discover that it was built above the resting place of Prince Renaissance, the Alicorn God of expression, music, arts, prophecy, poetry, and archery, the giver of musical talent to ponies, and the father of their colorful candy-colored themes, appearance, and architecture. Guarded by a group of spirits called Muses which predict that Backgammon's plans will result in the destruction of Equestria, and thus are intending to destroy all historical knowledge and archives and restart it from scratch to prevent this from happening, the heroes instead have a better solution to stop Backgammon for good. Now they must stop her before this prediction comes true and before the Muses annihilate all historical knowledge in Equestria.