Shadowglass Time-Magic, Blood-Magic - Shadowglass Series, #1

"Too late we realized for magic to survive, witches must survive."Magic has almost left the world entirely. The last piece of Shadowglass vanished centuries ago. Since then, the vampires have hunted down almost all of the Aeorian time-witches who could wield it, with an insatiable thirst for blood and magic. Now, in the final winter of World War II, a piece has reappeared-in the clutches of a dark and timeless enemy, in league with the Reich.
Emboldened by the possession of the Shadowglass, dark magical forces are gathering to turn the tide of war, and extend their dominion over all humanity. A rag-tag group of extraordinary beings-some out of myth, some out of legend-must band together in an attempt to retrieve the Shadowglass, defend the last the Aeorian time-witch on Earth, and defeat an enemy as ruthless as time itself. Shadowglass Time-Magic, Blood-Magic is Book One of the Shadowglass Series