The Red Sword Trilogy

Markal, an apprentice wizard, is thrust unexpectedly to the head of his order when his master is decapitated by a gray-skinned assassin. The order's walled gardens have the power to restore their dead master to life, but only if the apprentices can protect his body long enough for their sanctuary to work its magic. When a barbarian warrior named Bronwyn invades the gardens wielding a soul-binding sword and accuses the order of harboring a powerful sorcerer, Markal thinks she is another assassin come to finish the job.

When Nathaliey, a young wizard, is taken prisoner by marauders trying to break her will and force her to join the sorcerer's acolytes, the last help she expects is from the griffin riders who have harassed her and her companions through the mountains. But when their chief rescues Nathaliey from an enemy-held castle, the griffin riders join a temporary alliance of wizards and paladins to push back the sorcerer's invasion.