Usage Die

The usage die is an abstraction that is used in lieu of strict recordkeeping of every last ration, drop of water and ammunition.  You can use this system to see if you are meaningfully using up your resources by only tracking the resource as a whole.  It also gives a little “swing” to the numbers to play into tension, in that resources may be used up more quickly and than expected (by say, spoilage or breakage), or might even last a little longer (good quality, recovery of resources after use), but on average this is how long one could expect them to last.

An item represented by a usage die is marked with a die type when you acquire it.  This gives a notion of the number of uses that you may expect on average to get out of the resource based on the probability distribution of the roll (see below).

Every time you use the resource you roll the die type listed.  If you roll a 1 or 2 that resource is partially consumed and is now represented by the next lower die (d30 ⇒ d20 ⇒ d12 ⇒ d10 ⇒ d8 ⇒ d6 ⇒ d4).  If the resource die is d4 and you roll a 1 or 2 the resource is used up completely.

Bundles, cases or quivers of ammunition are also represented by a usage die.  You roll the usage die after combat to see if your ammunition is partially depleted.

The exception is if you roll a natural 1 or 2 to-hit during combat while using ammunition.  If you do, you must immediately roll the usage die for that ammunition to check for depletion as normal.  This helps give tension during combat as you can potentially begin using up your ammunition or even run out during combat.

All magical ammunition is strictly tracked and not reflected by a usage die.