I don't know if someone already stated this, but I'm going to give my suggestion (I'm not a BW expert, but i have an alt at 40).
I believe that the "ricochet" concept is what suits them better (even lorewise i think), but a change is indeed needed.
Now you don't bother about the damage because the spell that you use is going to be effective as well, so you are still dealing damage and doing your part, but what if you don't cast the spell instead?
What I propose is to change the straight damage tied with the mechanic's resources, and to introduce a "miscast" chance, where the spell isn't cast and it applies to the caster himself, with a proper % modifier tied to the current combustion. In this manner you can't sit at 100 because if you miscast some part of your rotation on yourself is totally devastating and not worth. This will be a huge nerf, I know, however if you grant these two classes a straight buff at low mechanic points, and a huge one at full potential, it could be worth it.
In addition, some abilities that "dump or discharge" combustion are necessary to keep a balanced way. (more than meltdown and burnout) or maybe change these two.
But let me make an example, and don't mind the numbers:
-from 0 to 50 ponts you have no miscast chance at all. Then each X point you increase your miscast chance untill 35% at 100. This increase should be exponential, not linear, in such a way to punish the 100 combustion sitting only.
-the same pattern must be applied for the buffs. You get a linear and modest buff untill 50, then an exponential one untill 100 where you get an huge crit chance and also a dmg boost (or something like this).
Let me explain the miscast part:
If you miscast a spell, it's symply applied to you, if it's a dot you will dot yourself---> your offensive stat will count against your defensive ones, and the damage should be scaled in proportion of your combustion level (like 100% dmg at full points and 50% at 50).
If it's an aoe spell, the aoe effect will be ignored, only the ST aspect will be considered.
Finally I will give a spell like Shield of Ashquy like 80% (or a high %) of miscast reduction, in such a way to have a free moment of rampage at full potential, however, if used incorrectly it will lead to certain doom.
-This will still be viable in solo-pug enviroment, where you can stay at a safe zone of 50ish points (BUT you have to manage this) with low risk and modest performance, and some 10s of rampage where you can be effective. And some will argue that this could be op, but if done properly it wouldn't, because 10s aren't much (considering the cast time and the HTL buffs to disrupts) and you have to build your combustion, so you need to choose: Do I use this early during the combustion building or do I use it at full throttle? Each decision has it's pros and cons (less dmg for the first but more safety, and more dmg but more risk for the latter).
-Also this treats the bombing/AOE aspect, where under focus you will not be able anymore to sit at 100, except if you have a coordinated heal focus, and this will lead to coordination and bear in minnd that if you are focus healed it means that others are not.
I'd like to pass only the concept, while the tuning will be more complicated, so don't focus on the nubers pls.
Sorry for the wall of text
