The Wizards of Once
The first book in the Wizards of Once series.
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...