Emperor Forged - K D Robertson - Bog

The emperor is dead. Betrayed. Now a new ruler must rise from the ashes.
Mykah had been the Empire's greatest general before it had rotted to corruption. Now he builds his own empire in order to crush the greatest nation in the world. At his side is the stunning woman who leads the horned barbarians from the north, known as the oni.
The Empire's armies are limitless. They have dragons, vampires, scores of mages, space-bending foxes, and more patriotic knights than one can imagine. Their industrial network can outfit an army in days.
Sometimes, winning requires a lot more than just a good army and tactics.
Mykah is up against the clock as the Empire rushes to crush his rebellion. He needs to find an edge over his opponent. His old allies turn on him even as he gathers new ones: elite sorceresses, energetic berserkers, and the horned beauty that leads the oni.
Establishing a new empire is hard. Mykah needs to do it before his past catches up to him and grinds him into the dust.