Let's Talk About Character Resources To Power Abilities

[dbm]

I loved recharge magic in th 3.x Unearthed Arcana

Interesting, I’ve not read that one previously.

There are some similar but opposite systems like ‘mana accumulation’. In the GURPS version of this, a spell needs a certain amount of mana and mana is aspected (think elements but other classifications can be used) and the caster makes skill rolls each round to accumulate power. Depending on your roll you might get exactly what you are looking for, a different type of mana, or none at all. When the mage has accumulated enough mana the spell is cast and if the mix of mana is not as originally intended the effect will vary from the caster’s absolute intent. I think this system came in via the GURPS implementation of Castle Falkenstein, so perhaps that system also had magic that worked like this?

Another interesting optional magic system in GURPS Thaumatology is ‘threshold-limited magic’. In this system, the power for spells is, again, not coming from the mage but from the environment. In this system, however, you keep a tally of all the magic that has been used in a location (within a reasonable time period - mana re-accumulates with time). The more mana is used in a location, the more risky magic becomes to use. And the interesting side effect of this is that all mages in an area are pulling from the same source. So this will create a group dynamic when there are multiple spell casters in a party, and NPCs also use the same power source so a conflict against a group with enemy spell casters is again a different kind of dynamic to ‘the norm’.

 

[Milieu]

I have never minded x/day (or long rest) abilities, but I do think it's perhaps more interesting to make them unlimited with a cost or a risk for overdoing it. What I do mind is when they make the tracking more complicated:
Barbarians get x rages/long rest, but get 1 back on a short rest, and at level 15 get an ability that refreshes all uses of it, 1/long rest, which is another resource to track, instead of just giving you more points.

Several abilities in 5.5e let you cast a spell without using a spell slot x/day, which is another resource to track. This also has interactions with the new version of the not casting two spells in a turn rule, which only applies to spells that use spell slots. So the first use of the day can be cast the same turn as another spell, which is more fiddly.

Fighters can have weapon mastery in x weapons at a time, but can swap one out per long rest, which means they functionally have mastery in the weapons they're using almost all of the time, except when they just found a cool magic axe or want to do something fun with an improvised weapon. But you're still supposed to track it because those edge cases might come up.

I don't think the juice is worth the squeeze in cases like that. I prefer more vigorous application of the KISS principle. If it's virtually unlimited, make it unlimited and eliminate the tracking. If it's not, keep the number of currencies to a minimum and have most class abilities draw from the same pool (or a small number of pools; I think it's fine if paladins have lay on hands points, smite points, and channel divinity points). Avoid currency conversions unless it's really cool (spending HP to push yourself is probably the only time it's really cool).