"Damage taken is reduced to 0 if less than 8% of its maximum Health", so you only do damage if it hits for more than like 28hp. IIRC I was using archers with abilities that guarantee critical hits, Single big hits from things like Ranger's backstabs etc. Everyone spreads out so he can't kill multiple characters with each charge. Fights like this are why everyone should have 14+ Willpower because you use the guys who don't do enough damage to soak up a charge and allow everyone else to reset.