LoS BB

for the MP Drain dmg room we don't see any msg of what we feel.. not even some vital energy is running away from us.. nothing

when we are in a place and we receive dmg.. from evil in a good area.. a good in a evil area.. room filled with fire.. cold.. stunned.. they all have msg

I agree on that. Usually it's the air that does some physical damage to you. But what's causing the mp drain is not known, nor how you feel the drain.