This story is a sequel to The Fiend that heralds Dark Skies

(This story is the sequel to The Fiend that heralds Dark Skies, which itself is a sequel to The Mare that eats The Monsters. Reading the first 2 stories is STRONGLY recomended to understand anything in this one.)

Twenty years ago, Princesses Luna and Twilight Sparkle were turned to stone and hidden away from Equestria by an old monster, once a pony, named Luminous Horizon. His intent was to release them when Equestria was nothing more than dust and rubble as retribution for the pains he suffered at Luna's hooves. They will be released before then, however, thanks to the efforts of Palmwood, Wonderboom and Moonrise Drifter. Together, they intend to set the imprisoned princesses free and bring an end to the unyielding darkness over the world.

This third and final story in the series will see the thousand year conflict end; for better or for worse.

This story is a sequel to The Mare that eats The Monsters

(This story is a direct sequel to The Mare that eats The Monsters, and reading that story is highly recomended to understand what's happening in this one.)

The horrors of that one night are still fresh in the minds of everypony in Equestria, even now, two months later. Hundreds of ponies were mercilessly slaughtered and Princess Celestia was killed by Luminous Horizon, her duties falling to her younger sister. Despite how confident she had seemed that her sacrifice would not be in vain, things have only gotten worse since then. The sun's light is begining to fade, casting the world into an unsettling eldritch abyss.

With the sinister omen of the sun's waning light looming over all of Equestria and the hunger of the fiends ever growing, Moonrise Drifter now pursues Luminous Horzion, eager for answers and vengance.

The story of 'The Mare that eats the Monsters' is an old, but still very well known Equestrian campfire and bed time story, often told to scare little fillies and colts into behaving themselves. It tells of a mare who loves Equestria and the ponies who live in it despite how frighteningly different she is. She protects ponies across Equestria from nightmarish creatures and monsters that would seek to kill ponies wherever possible.
What most ponies don't realize, but what Twilight Sparkle is soon to learn, is that the mare of the story was and is very real.

And the stakes of her mission have never been higher.

(This story has the horror tag, yes, but it isn't the dominant theme here.)