(the other post, about which door needed opening)I thought we were talking about this one:

But I guess you guys are missing the beckoning stone (required to open those doors) and are stuck at this door:

you reach after taking the teleporter on the left:

If that is the case, then you need th key to that door. From the two teleporters, go back down into the rift. Retrace your path of getting to the two teleporters.
After you leave the prisoners (3) area, go across the rope bridge (the one in the opening scene art) then instead of the path down the leads back the the lava cave in, turn right into the long halls.
In one of the 4 locked rooms, you get the key you need ... I think the sanctum key, or some similar name
Tools for Wizardry(r) 7