I'm using exhaustion more, but I threw out the PHB rules – didn't like them, none of my players liked them, too much "death spiral" for D&D (at least for our tastes).What ways of dealing with exhaustion in the game are there? Off the top of my head long rest and greater restoration.
I'm thinking of a game where you can gain exhaustion from.
1. 0 hit points.
2. Energy drain.
3. Critical hits
4. Environmental factors.
I’d allow the polymorph trick to let you ignore exhaustion until the polymorph ends.Potion of Vitality
Akmon, Hammer of Purphoros
True Polymorph into something Immune to Exhaustion (debatable)
That is how many DMs would rule it - but immunity is not well explained in D&D, and the plain English interpretation of immunity would say that you are exempt from any impacts of the thing to which you are immune, including the aility for it to "attach" or stay attached to you. If it is merely suppressed, you are not immune. After all, if I sold you a car that was "immune" to the need for gas, you'd be pretty ticked off when it stopped running de to lack of gas and I explained that putting gas in it before I sold it to you made it "immune" to needing gas ... for a while ...I’d allow the polymorph trick to let you ignore exhaustion until the polymorph ends.