KyleSchmelz
Fighter
Keep in mind that the target of a killing blow has to be immobile or helpless in some way. The 3-count to come into game represents the monster rising from the ground, running in from the edge of the battlefield, materializing from the aether, etc, so while they can't defend during that time, they're not immobile. Hitting them also gets their attention and doesn't have the same potential to confuse newer NPCs.