War God's Mantle: Ascension

The gods walk again …
When Marine Corps pilot Jacob Merely crashes during a routine mission off the coast of Cyprus, he was sure it was game over.
After surviving the crash and pulling himself onto the sandy shores of a long-abandoned island, however, Jacob unwittingly stumbles headfirst into the ancient ruins of a dead city. Unfortunately, he also stumbles into an age-old battle between good and evil—and he is now its newest recruit.
The island once belonged to the Amazons, daughters of Ares, the God of War, and stood as the final bastion between the human world and the monstrosities of the Great Below. But Jacob’s arrival has awakened the old gods and disturbed the seal holding the ravaging darkness at bay.
Now, with the help of a sacred gem containing Ares’ power, Jacob must recreate the Amazonian defenders of humanity and fortify the island stronghold. And if he fails, Hades will unleash his army of the damned and the world of men will fall, giving rise to an age of walking nightmares.