How do I get past the flame room in the level three dungeon?

timing. if you use haste you can get right across. If not you'll find that the flame is slightly off centre, and there is a point where you can wait safely. Just get your party across 1 at a time using that point.

And don't try to cross it over its entire lenght in one time. Use the various side-corridors to your advantage. Most important however, is -as Ironbeard pointed out- taking your party through one at a time.

Okay, I'll give it a try...just hope I don't get my ass roasted!!