The wizard hunters

“A mysterious army known only as the Gardier has surrounded Ile-Rien, attacking in ominous black airships. When a magical spell goes disastrously awry, young Tremaine Valiarde and a brave band are transported to another world. A world of rough magics, evil mages, honorable warriors - and a secret Gardier base.” - novel, first book in the Fall of Ile-Rien Trilogy - description from MarthaWells.com.