- Players traveling in less than ideal conditions should risk daily damage to Hit Points.
- The damage must be real Hit Points and heal in the standard manner - no extra bookkeeping.
- The damage should scale, so that high level characters do not outlast low level ones to a ridiculous degree.
- Easy to remember.
Base the AC of the 'Elementals' on how well the party is prepared for the condition. HPs based on how 'strong' the conditions are to over come.
Well, just a tip from your 'Uncle Larry',