He may have a plan. Remember, he knows defense magic, so he might just let the person/people wear themselves out on a shield them leave them lying on the ground due to mana-loss.
Any sniper knos that once they are found, their life is usually forfeit.
But, I have a feeling that there was a trap laid just for this situation, especially considering the best sniper in the world would already know this fact and knowing his opponent is a mater of tricks, would have one of...