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The Wizard Hunters (original 2003; edition 2004)
by Martha Wells
The Wizard Hunters by Martha Wells (2003)
References to this work on external resources.
Wikipedia in English (1)
Amazon.com Product Description (ISBN 038080798X, Mass Market Paperback)Ile-Rien is in peril. A mysterious army known only as the Gardier has surrounded the country, attacking in ominous black airships. Hope is not lost though, for a magical sphere created by Ile-Rien's greatest sorcerer may hold the key to defeating the faceless enemy. But the sphere is unpredictable and has already claimed several lives. 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.
(retrieved from Amazon Thu, 12 Mar 2015 18:18:31 -0400)
With the country of Ile-Rien under attack, a mystical sphere created by Ile-Rien's greatest sorcerer accidentally sends Tremaine Vallarde and others to another world filled with chaos, where Tremaine must unearth the secrets of the sphere.
(summary from another edition)