There’s a lot of other takes on Inspiration out there, and when to award it and so on. I’ve been toying with the below in my head for a while. Advantage on a die roll is nice, but having it to use for other things would be good too.
1. I know a guy
I think a lot of people are familiar with the ‘i know a guy’ rule. Basically having a way to grab someone useful at a moment’s notice, maybe from a character backstory or something, and dropping them in.
Spend the Inspiration to know a person who is useful in the current situation, and where they might be found.
2. Spell recharge
Sometimes you just need one more use of fireball for that boss encounter.
Spend Inspiration to cast one more spell that you’ve already used since the last long rest. Immediately gain a level of exhaustion. (DM discretion to allow this for uses of racial and class abilities.)
3. Roll a Hit Die
You forgot to take that rest before fighting the dragon, or you did and were all good to go, but then that minion got a lucky critical hit and you’re in trouble.
Spend an action and a Hit Die. Roll it and regain that many hit points.
Bonus DM usage. The villain gets away!
This is more of a way to give Inspiration. Great to use if the adventuring party works out who the spy or real villain is too early.
Every member of the party gets Inspiration but the villain gets away, turning them into a recurring nemesis.