Home brew or house rules for my 5e games
When something is expended roll to see if it can be re-used.
Poison Breath (Recharge 5–6).
This ability available on the Young Green Dragon. The dragon has this available at least once. Once used the DM rolls a d6. If it lands 5 or 6 then it has recharged for another use.
This is also seen with multi-charge wands with wording similar to “when you use the final charge roll a d20, on a 1 the wand is destroyed”
I initially encountered this mechanic on creatures in 5e as a way to limit their abilities without causing the DM to track so many different resource states.