Several conflicts are coming to a head. Visorak find a portal to Equestria in an abandoned castle just as Queen Chrysalis begins a new campaign. King Sombra, sensing the chaos, joins in. What will become of Princess Celestia's idyllic little empire, now besieged on every side?

This is a Bionicle - MLP crossover. It will be difficult to understand or enjoy it without some acquaintance with Bionicle lore. I would encourage everyone to take a look at Bionicle in its entirety, but for quick reference, here's The Bionicle Wiki.