God of Clocks (Deepgate Codex, Bk. 3)

In the cataclysm of the battle of the gods, a portal to Hell has been opened, releasing legions of unnatural creatures that have pushed humanity to the edge of extinction. While warring deities clash with fallen angels, the only hope for mankind's survival lies with the most unlikely heroes: Former assassin Rachel Hael has rejoined blood-magician Mina Greene and her little dog, Basilis, on one last desperate mission to save the world from the ravages of Hell. As Rachel travels to the final confrontation she has both sought and feared, she begins to realize that time itself is unraveling. And so she must prepare herself for a sacrifice that may claim her heart, her life, her soul--and even then it may not be enough.