Shadows Upon Time by Christopher Ruocchio

The seventh and final novel of the galaxy-spanning series merges the best of space opera and epic fantasy, as Hadrian Marlowe at last lights the greatest fire humanity has ever seen. The trumpet sounds. The end has come at last.

After his victory at Vorgossos, Hadrian Marlowe finds himself a fugitive, on the run not only from the Extrasolarians, but from his own people, the Sollan Empire he betrayed—and who betrayed him. Hidden safely beyond the borders of human space, Hadrian awaits the arrival of the one ally he has left: the Jaddian Prince Kaim-Olorin du Otranto. What's more, the inhuman Cielcin have vanished, unseen for more than one hundred years.

The armies of men have grown complacent, but Hadrian knows the truth: the Cielcin are gathering their strength, preparing for their final assault against the heart of all mankind. Only Hadrian possesses the power to stem the tide: an ancient war machine, forged by the daimon machines at the dawn of time. The mighty Demiurge.

With it, Hadrian must face not just the Cielcin horde, but their Prophet-King, and the dark gods it serves—the very gods who shaped the universe itself. This must be.