Savior of the Damned - The Guardians of Gaia, #1

The world is at the mercy of the necromancer Aurelius. In two centuries' time, he has risen, leaving untold destruction in his wake. With mysterious origins, his unfathomable motives have left remarkably little left of Terra to save. His only surviving adversary is Temple, an organization determined to bring his reign to an end.  Enter Phaedra, Demeter, and Eldren, friends who survived the destruction of their city as children and took shelter at the seat of Temple: Sanctuary City.
Growing up together, Phaedra and Eldren found their places within Sanctuary's walls. Fate, however, had other plans for Phaedra's sister Demeter. As a child, Demeter was declared the Chosen One to save humanity, with Phaedra left to her own devices. But now Aurelius knows of Demeter's destiny and has set his sights on corrupting both her and Phaedra. Now the sisters must navigate through abduction, forced servitude, and a new sense of self as their world faces new levels of increasing danger.
Meanwhile Eldren, now on the other side of the battlefield, is trying to reach the sisters in a bid to save them as well as the world. Will the greater good overcome? Or will they bow to Aurelius' demands?