Long before the Age of Alicorns, Artifacts were made and conceived. They had otherworldly powers, and each was dangerous in their own way. One was the Mirror of Souls. And now, it has been activated again. Strange new beings are appearing, a disease is spreading, and Equestria is doomed...until four creatures appear, each with its unique abilities. They are Equestria's last hope.

P.S. Dark Souls crossover.
P.P.S There are no sex scenes in this story, but allusions and nudity do apply.