The Brotherhood by Lucian Bane

Men of blood.
Men of God.
Men of machines.

A brotherhood hardened by survival,forged in battle and engineered for destruction.
While the Master of Mayhem tears civilization down to the bone, another evil rises in the wake—an enemy older than man, waiting beneath the abyss to ensure no soul survives.
The Bayou Bishops, the Viking Lords, and the Quantum Kings were never meant to fight together.
Their worlds don’t belong on the same battlefield.

But if there’s anything left to save, this unlikely brotherhood is the last line between survival and extinction. Brotherhood is their weapon. The swamp is their stronghold. And this war?
It’s only just begun.