Rune
Once A Fool
Personally, I don’t think so. But I’d also let Lesser Restoration remove a level if the recipient doesn’t have more than two.I like this one and wasn't sure how to implement it. Using the level of exhaustion (5 HD for the 5th level recovered down to the 4th) might work. It would be very taxing, but I like that as I want them to be a real decision if to use it or not.
Is it too taxing, though?
I like that exhaustion gives the DM a way to say, “Some challenges are just bigger than your hit points.” I wouldn’t want to trivialize that by making it too easy to remove.
But, as is, it is so punitive as to be under-utilized, because, without some good way to proactively remove at least some of it, it bogs play down with failed rolls. And that’s assuming that the exhausted characters haven’t become the real liabilities that they’ll be with more exhaustion levels!
Of course, the direction you count matters when you’re figuring the cost. For a more forgiving scale, start at the low end. First removed costs 1 HD, second costs 2, and so on.
Less forgiving: highest levels have to be removed first.