Frostborn

Ridmark Arban is the Gray Knight, questing to stop the return of the terrible Frostborn to the High King's realm. Yet the soulstone, the instrument of the return of the Frostborn, has been stolen by a ruthless cult and secured within the grim fortress of the Iron Tower.
And Ridmark must risk everything to retrieve it.
Mara wishes only to live peacefully. Yet her father was a dark elven wizard of power, and his shadow-tainted blood flows through her veins, threatening to transform her into a monster.
Yet that is not the greatest danger she faces.
For the Iron Tower was once home to an ancient evil, an evil that desires to claim the power in her blood . . .