Wrath of the Demiurge — A.J. Cooper

The Demiurge's legacy of evil has been largely forgotten; the memory of his reign of terror, almost vanished.
Yet Gaia -- having bridged the gap between her world and his -- ushers him once again into the world of the living.
As Eloesus slips into total war, the hero Theron hides away in a secluded mountain. Under the guidance of the centaur Aigon, he flees danger, even as the Demiurge's shadow falls across the land.
The fifth book of the Wind of Destiny series.