Shadow Magic — B.V. Larson

In Shadow Magic, the third book of the Haven Series, Herla of the Wild Hunt makes his move to gather all the Jewels of Power. Hunting down and killing those who wield them, the undead king is as relentless as death itself. He is not the only interested party, however, as several armies march to meet Brand and his allies in a desperate battle for control of the River Haven.

Shadow Magic is a little longer than Sky Magic.