The Wizards of Once Tome 1

From the bestselling author of How to Train Your Dragon comes an exciting high-adventure series - set in an ancient, magical time, full of Wizards, Warriors, Giants and Sprites. Winner of the Blue Peter Book AwardThis is the story of a young boy Wizard and a young girl Warrior who have been taught since birth to hate each other like poison; and the thrilling tale of what happens when their two worlds collide.
Perfect for boys and girls who love fantasy adventure... Once there was Magic, and the Magic lived in the dark forests. Until the Warriors came... Xar is a Wizard boy who has no Magic, and will do anything to get it. Wish is a Warrior girl, but she owns a banned Magical Object, and she will do anything to conceal it. In this whirlwind adventure, Xar and Wish must forget their differences if they're going to make it to the dungeons at Warrior Fort.
Where something that has been sleeping for hundreds of years is stirring...