- How many dice should it take to offset a status?
- Who gets to say what form the status/result takes in the fiction?
- What order do things happen in?
- How big an advantage is 1 die?
- How does this map over to multiple combatants?
How many dice should it take to offset a status?
I touched on this earlier, and one commenter gave some useful breakdown, and the short form is that this is a surprisingly tricky question. If this number is fairly low (say, 1 die per) then it makes dice differences more potent because it makes it easier to smooth out any short term advantage that a smaller die pool might have achieved. Not sure if that's good or bad, but it's important to know.
This also plays interestingly into the question of how target numbers are rolled for, because there is some question as to whether and how players can -try- to recover. This is not totally black and white, since I think it might not be unreasonable to say that if you really want to focus on recovering, pick something other than attacking (with a target of 4) and do that.
Lastly, we get some interesting effects if the pricing is inconsistent. Damage could become "stickier" if it becomes more costly to remove (or reduce) a status.
But in that, I think we might have our answer - reduction. If the "cost" is 1 die per 1 step reduction (rather than total removal) then it has two interesting effects. First, it makes it harder to clear the board - totally removing a severe effect - so the more severe the effect, the more implicitly costly it has become. Second, it means that even with mitigation, the accumulation of statuses is dangerous. That is, if you are already inconveniences and harmed (or whatever) then you can't just bump a taken out result down 1 to save yourself - you need to remove it entirely.
There's also some asymmetry to deal with. The steps for inflicting a status are big, so leftover dice are going to be more common than statuses, and that's a problem, since it invites fights that never end except at the very high and very low skill ranges. Some of that will hopefully be mitigated by other things you want to spend overage dice on, but that's a weak prop.
So with all that in mind, I think the right answer is to make the price consistent, but slightly higher - Allow 2 overage dice to reduce (but not remove) a status.
Who gets to say what form the status/result takes in the fiction?
Touched on this yesterday, and for the moment, I'll stick with the target defining things (with the possible optional rule of allowing the attacker to define things with a higher roll).
What order do things happen in?
Ah, now there's a bit of a bear. Initiative.
I cannot think of an initiative system I've ever actually liked. Round robin works ok, so it's all the way up to tolerable. Speedy action based ones (Shadowrun, Deadlands) make me crazily stabby. Shot Clock ones (Feng Shui, Exalted 2nd) always seem promising in theory but always prove more work than they're worth in practice. I could totally cheat the whole issue and go for scene based resolution or some other abstraction to escape the question entirely, but I don't actually enjoy things like that (with the exception of how The Shadow of Yesterday handles it, which I'll probably steal).
The reality is that I'm probably going to be forced to go with some sort of round robin/turn taking model out of brutal necessity, but I don't have to like it, and I can work to avoid things like "Declare up, resolve down" because part of what I'm trying to avoid is the big pow-wow between each round of combat. If action isn't fluid then it's less fun for everyone.
Honestly, initiative is one of those areas where I really prefer GM instinct and dicelessness. That is to say, while numeric initiative totally makes sense when everyone is part of the big picture (as in the case of, say, a tactical minis skirmish) that's not how fights work in fiction or perception. They are lots of miniature stages within the large picture, and we (as audience) move from one to another according to the cadence of the fight. A good GM can use "initiative" as that audience, moving from place to place according to the logic of the fights, not according to some numeric counter. Doing so covers a multitude of sins, allows for characters with different levels of combat focus to get different levels of attention while still keeping the spotlight from lingering too long in one place.
But that's not something you can really write a rule for. That's a problem.
So, honestly, my take on it is to make the official rule very simple - literally just go around the table rather than do any weird rolling or anything - but provide guidelines for initiative as cameraman. Mechanically, we might allow some rules for speed tricks using unused dice or the like, but those are for exceptions - character for whom speed is a schtick. In the absence of that the role of initiative is to keep everyone playing and engaged, not to reward the guy who found the best mechanical abuse of the system.
How big an advantage is 1 die?
Pretty big. In the end, if a 1d advantage means an 80% chance of success, I'll be happy. Obviously, there's a sliding scale to this - 3d should beat 2d more reliably than 5d will beat 4d, but that's my ballpark starting point, with a roughly 10% margin of error. However, I expect abilities (ways to spend dice) will throw this off when I get to them, which is fine.
How does this map over to multiple combatants?
This is the most important question to apply to any combat system. It is not hard to come up with a brilliant, clever, intricate system for handling 1-on-1 fights which utterly fails to account for multiple actors. Some of them try to apply duct tape solutions, like trying to make everything into chained sets of duels or aggregating opposition, but you can see the seams when that happens.
There's also an important genre consideration to how numbers work. I hate to invoke realism, but I'll do so in this very broad context - being outnumbered sucks. One man can absolutely fight a larger number of opponents, but doing so is dependent on a lot of factors, most of them involving finding a way to keep them all from coming at him at the same time. This is important, not because of how you model tactics, but because it's very important to _society_. It's what makes armies and police and many other things work. It also matters to style. The number of people one guy can fight speaks directly to the genre of things. In a gritty setting, even badass will run from groups of lesser adversaries, but in very cinematic settings, those adversaries are probably mooks, and can be easily dispensed with.
I'm definitely looking to avoid mook rules, though that's a whole other discussion of it's own. They're easy to add if a specific genre demands it, but I don't want them as a baseline. I like ganging up to be dangerous because of the aforementioned social element (and, in fact, this sentiment is all over the Fate 2 combat rules) but I think I may have implicitly handled that already. Since status mitigation depends on excess dice, the simple reality is that multiple opponents are going to burn through your dice in no time at all, even if they're not hugely dangerous individually. That's just a gut answer for now, but I think it will do.