Added OP question - How do you think it would play in 5E if the cost of using certain high levels of magic aged a character or if major amount of healing all at once caused aging (like half or more of HP in a single 24 hours)?
I like things like that in principle, but in practice it does create some strange balance issues between the races. Your half-orc barbarian probably gets healed a lot, so he'll die young (so to speak), while your elven wizard has an even bigger advantage in expected lifespan than he already did.Added OP question - How do you think it would play in 5E if the cost of using certain high levels of magic aged a character or if major amount of healing all at once caused aging (like half or more of HP in a single 24 hours)?