A Necessary Heresy by Davis Ashura

Prophesized heroes are reborn. The burden they bear is as terrible as it is necessary.

The dead city of Mahadev. In three thousand years, none who have entered those ageless walls have returned to bear word of what evil lurks within. And yet it is there that Cinder and Anya must journey. A hard road with mysteries and dangers abounding.

And the greatest of those perils is imprisoned within the ruined temple at the very center of the necropolis' dark heart. There, Cinder and Anya are given insight into the terrifying truth the world faces. It is an evil so vast that even the dark god, Shet, must bow before its will. It is the bringer of apocalypse, the ender of civilizations. If ever freed, the world will be helpless before its horrific power.

Forging an alliance all would have rather avoided, Cinder and Anya have no choice but to work with Shet to take on this greater enemy. Worse, it is a pact that will see them give away that which they hold most precious...