(Not a Dark Souls crossover, cover image coincidental.) A hero is sent to Equestria at Celestia's behest. What could possibly warrant the summoning of such a powerful warrior during times of peace, and why do these Ponies keep bothering him?
Talking sword? Sure. Talking horses? Bit weird, but okay. Hunters after my head? That's a bit different. So much for the vaunted love and tolerance of the ponies.
Stop me if you've heard this one: It's raining, and two of the gods you worship pop out of nowhere and send you to Equestria to fight for them. Not only that, but magic is on the line, though not just any magic: Song magic.