Rage of the Old Gods - The Books of the World Spectrum, #1

Humanity was not born free. Long ago, humans were slaves to the Old Gods. They rebelled, overthrowing the Gods and establishing their own societies, but peace did not last. Humanity slaughters itself in petty wars. Now, an army of war Automatons threatens to destroy the land of Eastenhold. To save her people, a young woman named Leha travels to the to the lost worlds of Tyzu and Sy'om, whose alien powers defeated the Old Gods in ancient times.
But there is worse to come. The wars of humankind only hasten the Old Gods' return, and even Leha's newfound powers may not be enough to save her people from the Gods' fury, or from the hatred in their own hearts.