Soul of Serpents — Jonathan Moeller

A story ten years in the making, here at last is the triumphant third book of the "Demonsouled" series. Mazael, now Lord of Castle Cravenlock, faces his darkest challenge yet. A horde of inhuman fiends has descended upon the Grim Marches, slaying and killing. The priests of the serpent god lurk in the shadows, scheming vengeance upon Mazael...and upon his family. But both the fiends and the priests of the serpent god serve another master, one who plots to seize the throne of the heavens itself, a foe that even Mazael's skill and valor may not be able to defeat...