A Fate/Zero crossover of sorts.

Equestria is dying, and always has been.

The whole world has been this way for a thousand years, ever since Princess Celestia sacrificed herself to bind the fallen Princess Luna. Year by year the soil turns barren, the oceans turn still, the sun glows colder, and civilization slowly crumbles. The pegasi have not controlled the weather for centuries. Soon, the unicorns will lack the strength to raise the sun each morning. The world will be bare of life in less than two centuries. Even the most powerful magical artifacts cannot halt the decline.

Until now.

An old power has resurfaced, and five ponies race to claim it. A young duke, desperate to save his city and reclaim his family honor. A bounty hunter who speaks to the earth. A scion of magical power. A purposeless prodigy. And a college dropout. They will raise powerful servants and fight for the Grail of Magic.

Dark factions plot on the horizons and strange beings peer in from outside places. One master of magic will claim the Grail. They will save the fading world... or rule its ashes.