Guardian of the North - Descendants of Robin Hood, #1

Eight hundred years ago, a powerful sorcerer laid a trap for Robin Hood. But the curse backfired, releasing a burst of pure magic. Robin Hood's descendants carry this magic as elemental powers. The two nations of descendants are on the brink of war. Jack's North Wind power is about to manifest when the rival nation attacks, hunting the last Wind. Jack is forced to abandon his court in a fiery escape.
Now he's on the run from the mercenary Sheriff, sorcerers, and a mysterious girl of the shadows as he struggles to contain his chaotic power. Rumors grow of the ancient sorcerer's return, and Jack is faced with the horrifying realization that his power is part of a much larger plan. The rival nation has discovered a secret weapon, and Jack is the last Wind keeping them from unleashing its ancient magic.