My main issue is boon hoarding.Do you have any examples?Also, I see potential for game-breaking practices like boon hoarding.
At most i see a likely critical hit, but if that is from a whole party giving up their attack to help facilitate, it is not really a massive amount of damage.
The only time boon stacking makes sense, is for attacks rolls as far as i know, but maybe i am missing something?
I can see many/most rolls receiving no less than two or three boons:
One is for help
One is situational like from a spell or Heroic Ability, if not both.
One is for gear
This kind of forces the GM into an arms race to apply banes, doing otherwise takes out any risk from dice rolling.
And if you end up actually rolling with 3 boons, failure chances are very likely so minimal that I wonder: why bother rolling?
The reverse is also true, if you end up rolling with 3 banes, you are probably doomed to fail unless you have a staggeringly high skill-level.
This becomes kind of a zero sum game, and makes character skill less relevant, imho.
My 2cp