
HappyHuman |

This is about 4% of a useful idea - anyone remember the Dark Millennium system for psykers in Warhammer 40,000?
Spells(powers) cost 1-3 force cards to cast, and each turn you'd deal nd6 cards where n was the number of psykers(casters) in the fight. The effect was that in smaller fights a psyker got a trickle of power and couldn't blow everything up unless the deal was really lucky, and in a huge fight there was boatloads of force available and everybody could cut loose.
In theory, "fight size" is already handled; every encounter is trivial, extreme or whatever. What if caster power scaled with that somehow? As an elementary example I've given about two seconds of thought, what if casters got one "unit of spell power" to use in a trivial fight, two in a low fight, et cetera, up to five in an extreme fight? Assuming the numbers were brilliantly chosen you wouldn't have "conservation" fights and "nova" fights; in every fight you'd have roughly-enough power to call on and it would be up to you to get as much value out of it as you could.
(Lore-wise, this was easy to explain in 40k because conflict and death stir up the Warp and the Warp is where psykers' power comes from. I feel like that general idea could be copy-pasted, even if we admitted that the mechanic's real raison d'etre was to help with power allocation.)