After stumbling upon a great secret beneath the Everfree Forest, Twilight and Rainbow Dash are cast into a world of forgotten civilisations, ancient Forerunner technology and tragedy on a galactic scale. This discovery could surely mean an advancement of epic proportions for the Equestrians? Or perhaps a fate far worse than death...
Twilight and Rainbow will soon learn that despite the creators being long forgotten, the created remain a threat.
NOTE: This is a different take on the standard Halo crossover; rather than a spartan in Equestria or a pony in the Halo world, this brings the myth akin to Cryptum and Primordium.