Spiritwalker Trilogy, book 2: Cold Fire
Kate Elliott2011

Cat and her cousin are key players in a drama of dragons and politics. Everyone wants something from them - including the warlord who's conquering all Europa and the Cold Mages who dare defy him. But the Master of the Wild Hunt is most dangerous of all. He will command Cat's loyalty using what she holds most dear. In a world where science and magic are at war, one girl must save those she loves, or lose everything.