Blood for Blood- Ryan Graudin

“Yael wanted to be like the Valkyrie maidens in the old Norse lore. Winged women who rode to war on the backs of wolves, choosing which soldiers lived and died. She'd thought she could make death mean something, if she wielded it right. (A death to end this death.) So shed aimed her gun at that man in the ballroom and MADE HER CHOICE.” Sequel to: Wolf by Wolf. I don’t have the first book