I noticed that this place seems to be a common prob for ppl and decided to offer a bit of advice...
First off many fights are ez if u use this tactic, it's cheap but it works. Have your guys stand well away from the door with all their helpfull spells on them. Then summon a few of your favorite creatures and then haste all of your guys including the creatures. Walk a summon creature and a party member up to the door open it and run leaving your creature there untill a few of the bad guys chase it. Kill thoes then rinse lather and repeat as necessary.