The Scepter of Tuonetar. The Tuonetar Cycle, #4

The dead do not rest in the Lands of Storsen. They march. Driven by a fanatical faith in Tuonetar, goddess of death, the Necromancers of Dark Valley have built an empire of horror - transforming the living into an endless army of Undead to reshape the world in their goddess's image. As the fortified Monastery that serves as their stronghold grows in power, the fragile alliance between the Duchy of Peylan, the fierce riders of Tiros, and the wary Barons of the border may be the only force capable of stopping them.
Into this conflict steps an unlikely fellowship: a wandering bard haunted by guilt, a scarred warrior woman searching for worth, a steppe fighter bound by a warrior's code, a timid librarian discovering unexpected courage, a half-elf caught between life and death, and an Undead soldier fighting to reclaim his humanity. Each carries wounds - seen and unseen - and each will be tested to their limits before the war is done.
But the true battle may not be fought on the battlefield. Beneath the Monastery, older and stranger secrets wait to be uncovered - secrets that could shatter everything the world believes about gods, death, and the nature of power itself. The Scepter of Tuonetar is an epic dark fantasy of war, sacrifice, and the stubborn persistence of hope - a story about what we owe the dead, and what the living owe each other.