The Darkest of Wars by Scarlet Young

Death has descended.
The blood of shifters, wolves, and hunters scatter the landscape as the darkness settles among them for good. Witches are called to the front to aid in whatever hope is left to push back the Hunters, as Regina’s soul begins to slip away from her paling body.
Hope is crumbling.
Niko and Lyra know that any hopes they have of rescuing Theo and Reagan lies in New Bern, and so Niko must confront his former pack face-to-face in a desperate bid for help. However, their new leader is of no mind to aid the former Alpha, and so they must go it alone.
Even if Niko can break his fellow shifters out of holding, the looming threat of war hangs imminent in the air–and promises to bring carnage down on both sides whether or not their mission is successful. As shifters and hunters enter the rising din of slaughter and sacrifice, Niko finds himself at a crossroads in a war that may just destroy everything worth believing in.