I am on the 3rd level in the "lava pit" and I just can't figure out how to open the doors to the last staff piece. I've killed all the monsters except the liches which are impossible to defeat.On the 3rd level, there are no doors except in the center of the lava pit. You can get the Staff piece without opening those doors; you just climb the pyramid and hop over to the platform and get it. You have to answer a tough riddle to open the doors and get out, though.
I read somewhere that you could get in the east door, but not me.Not sure what this might mean, but all I can say is that you cannot open any doors on this level except by riddle, so whatever you read is either incorrect or perhaps misapplied.