I have this crazy idea of using affixes that set conditions for enemies in combat, i.e. traits. It's essentially the same idea, but without the stagger numbers. An affix can describe any kind of behavior that I can think of, which with I can control combat 'difficulty.' I got the idea when I watched some steamer on Twitch play Diablo 3, the other day. Some of the monsters in that game have 'affixes' that make them more difficult to fight against. I have yet to explore this idea, so I'm not going to change the combat stuffs anytime soon.