The lock opened with the ruby key as I expected, and behind it were some stairs up.
Upstairs there was an alchove with the Crown of Nerra, some fine robes and some sandals. I suspected something might happen if I picked them all up, and sure enough, I heard a click and took a deep fall to "surrender your possessions". I picked up the key there and stepped through a teleporter which took me to the area below Supplies for the quick, so I reloaded rather than running the long way back.
I looked up the stats for Crown of Nerra, and saw that it gives +10 wisdom. I gave it to Syra who has the lowest base wisdom of 63. I left the other stuff behind.
There was another lightning door that automatically opened when I stepped in front of it, presumably because I had corbums in my inventory, but I went past it because I didn't want to go up there again without all 4 corbums.
Further along the corridor there were some stairs down, and at the end of the corridor there was a locked door which I kept hearing fireball explosions behind, and a button on the wall.
I decided to go down the stairs first. Downstairs was an empty niche on the right, and an area with some pits on the floor and over head (one which was opening and closing). There was a path through the pits which led to the central pillar, and it had a dragon steak in it. I gave it to Nabi who was yellow on food.
By the way, 240 mana seems to be the next magic number as far as mana regen is concerned, because at 243 mana, Nabi seems to have noticably faster mana regen than the rest of the party at 228, 235 and 236 mana.
I went back up and went left towards the door.
I pressed the button on the wall, and it opened the door. I quickly stepped to the side, but the fireballs weren't being fired at the door.
To the left there was an inscription that said "Eyes lie", and to the right was a concealed pit and a fake wall.
Inside the fake wall was a button on the wall. When I pressed it, the concealed pit closed.
There wasn't any obvious ways to proceed from there though, but when I tried placing a rock on the pit in front, it turned out to be a fake pit.
I walked on top of the fake pit. I suspected that the pit in front of the corbum might be fake too, so I quickly stepped over the blinking pit when it was closed, and luckily I was right.
I picked up the final corbum, then made my way back to the stairs up.
Upstairs there was a 3x3 room to the left with some pressure plates along the walls with an empty spot in the middle. To the right were a couple of doors locked with Ra locks, one of which had a blue mist behind it. Further along there was a closed iron door with no obvious way to open it.
I saved the game and decided to try using my Ra key opening the door with the blue mist behind it first.
I stepped into the teleporter, and was confronted by a group of 4 demons. I started circle strafing them. I spotted another pair of demons nearby, so I stopped and started casting fireshields. The party got hit by a couple of fireballs before I was done casting all of them, so there were some injuries. Syra went up to Um master ninja while I was fighting them.
After I had killed the first group, I circle strafed the pair that was left. Afterwards, I saved in a new slot just in case.
I was in a big open room, and there was a blue mist to the east of where I had initially been teleported to.
When I stepped into that teleporter, I was teleported to an area with lots of demons, and a couple of zytaxes and worms. I put on some shield spells and stood there and fought them all, which took a while. My fireshields also ran out at some point, so I had to refresh them. Some of my champions had to drink a healing potion at some point.
When they were all dead except a couple of straggling demons nearby, I stood there and trying to get my bearings and trying to decide where to go next. Then suddenly Lord Chaos appeared in front of me, so I started moving away. Nearby I found the inscription "Demon chamber", and I found a Master key on the floor. I went into a dead end corridor, turned around with my back to the wall, and waited for a worm that was following me.
After I had killed the worm, I had Syra and Wu Tse make a healing potion each because they were injured, then I saved in yet another new slot.
I cast shields and fireshields again, then headed towards the demon chamber.
I didn't find any obvious way to proceed from there, so I started running around. I found out that the wall in the dead end where I had fought the worm was a fake wall, so I went through it and ran around for a bit, finding areas I had been the first time I had been on this level.
After a while, I found my way back to the demon chamber area again. I fought some demons, then pressed a button on the wall inside a blue mist. Now there suddenly were a lot of demons, so I went back to a narrow area and started fighting them. At some point my fireshields ran out, and I took some fireball damage until I was able to refresh them.
I then heard a teleport sound, and when I turned around I saw Lord Chaos had teleported to me again. I ran around trying to avoid being cornered between him and some demons, and eventually fell down a concealed pit.
I found some stairs up, and made my way to the demon chamber area again. I found a button on the wall which seems to have rearranged some walls when I pressed it.
I fought some more demons, then I ran around the room trying to find the black lock which I eventually did, and unlocked it with the master key.
While I was standing there unlocking the door, I was hit with some fireballs, and my fireshields had run out again. I slowly limped my way into the room, and eventually found the Fulya pit. I threw the corbums into it one by one, and finally victory was mine
Final stats:
Nabi:
Um master fighter
Um master ninja
Ee master priest
Um master wizard
Health: 712
Stamina: 668
Mana: 243
Syra:
Um master fighter
Um master ninja
Ee master priest
Um master wizard
Health: 713
Stamina: 763
Mana: 228
Wu Tse:
Lo master fighter
Lo master ninja
Ee master priest
Um master wizard
Health: 620
Stamina: 420
Mana: 235
Elija:
Lo master fighter
Lo master ninja
Ee master priest
Um master wizard
Health: 660
Stamina: 510
Mana: 236