Bailey Cove Sci-Fi Book Club: The Wizard Hunters

On Ile-Rien, a world besieged by the mysterious and well-nigh invulnerable Gardier, Tremaine is recruited to help devise a spell that can break through the Gardier airships' impregnable shields. Yet instead of creating a weapon, the spell transports Tremaine and a small band of cohorts to another world with a secret Gardier base, giving them a chance to spy on the enemy of which they know so little.