never let guildenstern use bloody sin (i think that's the name of his uber magic).how?before he uses bloody sin,the camera view shifts ABOVE you.and then he will fly over the battlefield through the center.it is then that you will have the chance to hit him.since you are always at the edge of the battlefield,i wud recommend bringing a crossbow along.when he passes above the field,hit him.even if you miss (i think),his bloody sin will be canceled.your 5-10 damage will increase to a decent number if you can chain well.but personally,i used break arts here,so as not to increase my risk to 100 or so.