You're playing a wizard in an RPG. You have a warrior cornered at the end of a box canyon. He has a medallion that renders your magic ineffective against his person. His fighting skill is so superior that he is the equivelant of 10 men. He has placed himself far enough away from the canyon walls so a landslide cannot injure/kill him.
One of you must die. How would you go about it? Use your imagination.