The Critmonster is a use of tactical precision to 'prep' the target for an aimed Ambush in the same location. So for example, a typical strike might be a Rogue knocking out the right knee of the right leg they are aiming for. Just before hiding, they use 'Critmonster' and use their knowledge of their mastery to aim just in a place which will soften the area in a number of ways, making it more vulnerable to critical damage. The Rogue successfully use Critmonster, pops into hiding and ambushes the right leg successfully. The monster is a Troll with unusually high crit resistance and also the ward was about +165 with a flaring blade-- but the leg flies off because the crit rank was raised from the like level Rogue who has mastered the Critmonster.