Exertion - another way to use hit dice

[MrStabby]

Yep, we want (if anything) more use of HD to heal to prevent "healbot" requirement from coming back.

A tweak I'm going to try is to make all magical healing require spending a HD as well, and that HD adding to the amount healed (with rare exceptions: mass heal, regeneration, heal, power word: heal).

This makes spending HD more of a thing, takes some of the load off magical healing (in terms of HP). Small magical heals are inefficient in terms of HD:HP healed, making an interesting tradeoff. And when you run out of HD, magical healing can't help you.

Interestingly I am currently trying something similar - though the HD is one per die of the spell and it isnt mandatory to spend a HD. So lay on hands is unchanged but others get a boost. Mixed results so far - the healing word/cure woulds disparity is bigger than ever but tankier classes feel tankier now.