From the comments and my own thinking it seems that the new solutions to the grind of high-level combat break into two categories: escalation of the numbers involved, and giving higher-level characters additional abilities and feats that help make combat faster and more interesting.
In both these classes, a solution should have the following features:
1. If optional, should give some self-evident advantage to the players using it, without mathy thinky gamey time. This rules out things like "you may optionally double your damage if you accept double damage against you," because using that optimally will require you to think in terms of who is likely to do how much damage and have how many hit points.
2. Should balance out the excitement between early and later rounds - either by shortening the number of "early" rounds to get to the crucial rounds (early-combat escalation) or by escalating the later rounds so they get more crucial (late-combat escalation).
3. Should deliver a different feel to the long-lasting high level combats, as compared to the short and deadly low level ones.
Let's consider escalation rules. This was actually on my mind because of the recent discussion of fatigue on A Paladin in Citadel. While most fatigue rules make people less competent as they get tired, that is realistic, boring, and drags out combat even longer rather than speeding and spicing it up.
Here, I'm leaning toward late-combat escalation, because it's a rule you can apply at all levels of play. If that fight against orcs grinds on, then I guess things get more deadly too ... but it's rare to see that level of combat last for more than six real rounds of action.
Introducing ... the escalation die.
It comes out when the first Escalation Event occurs, set to 1, and goes up by one for each subsequent Escalation Event. What is that, you ask? Just something that happens when one of two numbers is rolled on a d20 in skirmish combat for whatever reason - hit roll, saving throw, ability check.
If you don't have critical hits or fumbles, those two numbers can be 1 or 20. Otherwise, may I suggest lucky 7 and unlucky 13.
The effect is quite simple: the number currently showing on the die is added to all "to hit" rolls and damage rolls while combat is ongoing. The maximum value of the die is the level of the highest level PC in the fight.
For each round of break in the combat with no attempts to hit on either side, reduce the die by one.
Obviously, this shouldn't be used in mass missile fire, so only the PCs and their immediate foes are affected (that is, those fighting them).
Although I've yet to test this system on high-level characters, the good thing about it is that it lets the players get some fair idea of the capabilities of their foes, then tells them exactly how dangerous combat is getting as it goes along.
Researcher in social science and appreciator of hexy wargames, role playing games, interactive fiction, board games, and CCGs. I've learned a lot doing design and rules editing work on the side for the Legend of the Five Rings CCG. But this blog is mostly about other things.