The Red Winter

Rowan has won a battle, but not the war. WIth proper allies, Rowan's armies could storm Prusias's stronghold, capture its ruler, and end the reign of demonkind. But while nations clash, a greater struggle lies elsewhere.
In his desperate pursuit of Astaroth, the sorcerer Elias Bram scours time and space for clues to the fiend's origins and purpose. His terrifying discoveries hint that not only is humanity at risk, but the Earth itself. Its fate may depend upon three young heroes. With their matchless skills, it's up to Max McDaniels, David Menlo, and little Mina to tip the balance.
But Max McDaniels must face demons of his own. As Rowan's Hound grows into his birthright, he must choose which part of his lineage to embrace; the mortal youth who would save humanity, or the demigod whose power could win the war but also turn him into the very tyrant he would overthrow.
In the Tapestry's fifth and final volume, Henry H. Neff concludes an unforgettable series in which magic can live, gods can die, and the highest stakes require the greatest sacrifice.