Retribution (Chronicles of the Sentinels) by Jon Wasik

What happens when you piss off a Babylonian demigod? Chris, Alycia and Emmi have spent the summer training in the mountains to become Sentinels, honing their magic while learning combat skills. But on the day of their final trial, Nabu, very much alive and sporting a new body, launches an all-out assault against them. Nabu's only demand - return Imhullu, or she will exact revenge not just upon the Sentinels, but upon everyone they love. As the demigod carves a bloody and destructive path through the lives of the Sentinels, Chris must ascertain not only why Nabu needs the soul-consuming dagger, but also how to once and for all destroy her. The fate not just of his loved ones hangs in the balance, so too does the fate of every single human soul.

Legacy (Chronicles of the Sentinels Book 1) by Jon Wasik

Magic is real. Babylonian gods are real, and they’re hungry for human souls. But can a 22 year old Japanese-American college student, whose life has revolved around science, come to terms with the existence of magic, let alone defend the Earth from those hungry gods? For days, engineering student Christopher Tatsu has been plagued by bizarre dreams of gargoyles, magic, and a strangely beautiful, anime-like woman. Things get weirder when those dreams start to come true. Things like magic sand, a blue-haired gun-toting elf that saves his life, and a gargoyle bent on killing Chris and his friends. He’s just trying to pass his last classes and graduate, but he quickly finds himself embroiled in a conflict to protect the Barrier, a 4,000 year old planet-wide enchantment that has prevented most magic from existing on Earth, and by extension, has stopped a Babylonian god from feeding upon human souls. Will he come to accept the reality of magic? Will he save the Barrier? And did he pass his last final?