The Power of Efreet

One thing I have noticed is that many old modules with only access to the original Monster Manual as an official source of monsters, use efreet as high-level monsters.  I took a look at efreet to see what makes them so powerful:

They can basically give themselves the ability to do potentially close to 50 hp of damage per round and take their armor class down by 6 points and make themselves difficult to target by spells.  These abilities give a single efreet the potential to eliminate multiple characters in a matter of rounds.  Efreet probably have at least 50 hp and are going to be tough foes in combat.

Fighting an efreet is a risky proposition.