Been mulling over a bunch of different facets of action dice, and have come up with a few ideas to make them more user friendly and less GM twitchy.
One of the big issues with action dice is the weird (retrograde) math involved in exploding as the die size changes - and the near recursive exploding you can engineer on smaller dice. In waltzes the potential to get truely momumental results that have little impact on the skill system but blow the hell out of combat. Interconnected with that is the sudden death quality of combat crits which get used by players to make "boss fights" little more than a race to get a crit, while GMs get left out of the fun because one-shotting players makes you look like a prick. That in turn points to the issue of incredibly poor return on investment using action dice to refresh. Finally, the 14,000 pound elephant in the room is the Fortunate feat (and the half dozen other pachyderms hiding behind it in the form of about half the Chance tree...)
Phew. Ok, here's the summ of my cogitating all as one big block of changes.
1. ALL action dice are d6s. Player dice at every level, and GM dice. Cubes. All of them. Every last one. (this makes writing rules about action dice way, way more consistent)
2. Action dice may explode only once. +12 is the most a single die is ever going to result in (before modifiers). (Triumphs are gone, we don't need to track rolls of 70+).
3. When you spend 1 action die to confirm a crit on an attack on a special character, first roll the die and add it to the damage then either stun the target for 1 round or send them to the table of ouch.
Damage does NOT go directly to wounds. Crit immunity remains highly valuable. GMs, you may now feel free to stun the hell out of players. Players, you may now potentially lock down big bads with chain stuns, but action dice as the window to auto-slaying specials is as dead for you as it has been for the GM.
4. The Refresh action reads as follows~
Refresh (Full Initiative Action): You recover vitality points equal to half your Constitution score (round up). You may spend and roll exactly 1 action die and add the results to the number of vitality points recovered.
This is accompanied by 2 new tricks that may be bought with proficiences in the usual fashion for stand alone tricks.
Go to Ground (Refresh trick): You may also make a standard move as part of this refresh action if that move ends with you in a location that grants at least 1/2 cover towards 1 or more adversaries.
Take Stock, then Rock (Refresh trick): You may also take a use item action to ready, stow, or reload a weapon on you person during this refresh action.
5. The Fortunate feat now reads as follows~
Benefit: At the begining of each scene, if you have fewer action dice than you have chance feats, you gain 3 action dice.
The intent being Fortunate characters will want to blow through their dice, hoarding no more than their (chance feats - 1) so that they can get a free refill going into the next scene. If they have more chance feats than starting feats (a true chance-monkey build) they get their dice at the outset, but even then the bonus dice are capped at 3.