I’ve been reading the new Dr. Strange comic (which I highly recommend if people like either comics or Dr. Strange) and then saw a splash panel elsewhere of the comic book character Ilyana Rasputin holding the Eye of Agamatto and thought about how many magic items are described as having a cost, or are exhausting to use. Now, currently D&D uses some combination of the X/uses between a Short/Long rest to describe this and that’s certainly a reasonable way to do so, but it also doesn’t capture the sense of “exhausting” that I’m thinking of.
One way to do this is by activations or uses casting Hit Points. The problem with this is that there is also a trope about some magic or magical items needed blood or wounds to be used and for all the talk about Hit Points representing more than physical damage, they are still closely linked to that in most players minds. So again, the flavor is off.
So, how about Exhaustion? There is actually a condition mechanic for this in 5E – my problem with this is that the Exhaustion condition is very debilitating to characters and with six levels of it you simply die. So while this is a valid use of the Exhaustion condition, I would want to save it for the most powerful (or cursed) of artifacts or effects because the penalties are likely to cause many players from using the item or effect in question.
What I had actually thought of was using Hit Dice!
This makes Hit Dice a multi-use resource (always a good thing in my mind) that forces a player to choose between “useful effect now” and “healing later”. It increases as levels go up (so high level characters have more uses, something that I’m a fan of). I also think that Hit Dice as a concept is removed enough from Hit Points in that it can be equated to “endurance” or “exhaustion” as opposed to damage – especially since Hit Dice are regained through Long Rests.
Hit Dice are also generic enough to conceptually valid for Arcane Magic, Divine Magic, and Psionics. The cost can even be scaled if the DM desires so that smaller effect costs 1HD while a large one might cost 5HD or whatever (also neatly creating a minimum level for certain uses). This also opens up the idea that some items might allow (or even require) multiple characters to contribute HD to create an effect (especially for those big and flashy ones).
There is also nothing preventing a DM from using both Hit Dice and Exhaustion for really powerful items – or simply as the limiting factor in low magic campaigns. One could create items that have a Hit Die cost over multiple Long Rests. Something like a 1HD cost each day while a multi-day effect is running, or a 5HD cost that decreases by one after each Rest (or Long Rest).
In any case, I hope someone out there can get some use out of this. I’m certainly going to experiment with it myself!