ToME: the Tales of Maj'Eyal

So I encountered a strange vault, with lava in the middle, a couple teleporters, a whole bunch of locked doors with switches, and diggable glass. Flipped the switches back and forth, opened the doors, dug through class I could get to, killed the boss unique that appeared. But there was still one 3x1 room behind diggable glass I could not get to because of the lava. I could see there was a bow in the space right behind the glass, and am assuming the other two spaces had items as well.

Has anybody been able to figure this vault out?

Yes.

I would also like an answer to this question.

I see this is now in spoilers, thus I will spoil you . . .
I simply hit the levers one at a time, counterclock-wise starting on the right, killing beasts as they were generated. When I got to the 12 o' clock position and ran out of levers, I back tracked and hit each lever on the left side until reaching the last lever. I hit each lever only once. After all levers were hit, a big elite demon popped out from the area where the teleport pad is--kill it, hop on the pad over to the loot.

None of which tells us how to get to the loot inside the 3 by 1 walled-off space.