Just wished to shed some light on this; I think I mentioned this in another thread, but mummies actually never dies from fire traps, noone does. In worst case scenario, the Sim faints. However, indirectly they may die as I have had fire started by a fire or electricity trap in my home, but I've never managed to do that any other place, so it is possible that it may never occur in adventures. From those "real" fires however a mummy die instantly, but they can perfectly fine be used for adventures as I use my sim (who happens to be a mummy).