Thinking more of good and bad, when not in equal measure.
Again, this is one spot where I just emulated a 5e rule, since it seemed to fit. No matter how many instances of advantage or disadvantage exist there are four possibilities:
1. No advantage or disadvantage at all, roll 1d20.
2. One or more instances of Advantage, roll 2d20, take the highest.
3. One or more instances of Disadvantage, roll 2d20, take the lowest.
4. One or more instances of both advantage and disadvantage, roll 1d20.
The object is to reward tactics, and this does so, without all sorts of mathletics. So, if you're dazed and you're attacking with surprise, you just make an ordinary attack. At least you're not just getting the dazed penalty, and OTOH its not obviated by being hidden either. So this rule does the minimum necessary work, and avoids any sort of stacking, which generally breaks d20 games.
In full, the math of this game is pretty simple, you get an ability bonus (there is effectively always one), a proficiency bonus (always +5 when it applies), a level bonus (current .66/level rounded down), and a 'permanent' bonus, which accounts for ALL other non-varying possibilities, and never exceeds +3 (I guess it could, items never get higher than +3). Because none of these are especially situational, they generally don't vary from moment to moment (though they obviously not all applicable in every situation, but that is based on the nature of what grants the bonus, not the situation). The point being, since NONE of these ever stack, and there is no 'untyped bonus' that could, you pretty much play with fixed, known, bonuses which can be written down on your character sheet.
So, basically I looked at 4e's rules and removed stuff that made the 'in play' side more complicated. I want to pay attention to fiction more than intricate rules process. I LIKED 4e, but I'm old, and my brain does not want to wrap itself around lots of fiddly moving parts, (and this
@pemerton, is why I will never run BW, though I like the idea of PLAYING TB2, but
@Manbearcat will have the fun of remembering exactly what the invoking your nature rules do, lol).