Sometimes when you run a strike the post game screen will list super kills and if you're playing defender sometimes you'll have a number listed. My best guess is it's kills while under an effect of Ward of Dawn. For those of you unfamiliar with WoD's (bubble) effects they are Armor of Light - A regenerating overshield and possibly increased armor/defense while inside of the bubble Blessing of Light - ~8 second overshield whenever you touch the walls of the bubble Weapons of Light - ~8 second 25% increase to weapon damage whenever you thouch the walls of the bubble.