King's Domicile
This level is a swine to put it mildly. Check it out with True Seeing and you'll see a checkerboard of yellow. The place is riddled with spinners and trapdoors. All the trapdoors lead to The Lava Cellar, and I got sick to the back teeth of dropping down to there, trudging back, being spun and then falling through another trapdoor. To be brief, they are just a pain and a time waster.
Two bits of info from NPCs. One tells you that the elemental bound by the wizard is En-li-Kil and he commands time itself. Another says that in the King's Quarters is an elevator that will take you to the Palace. King Cleowyn used to use it to bypass the traps around his throne. (That is through the door at B2 which is opened using the King's Domicile Key, which you'll find at C14).
Stairs lead to the Great Corridor at P16 and there's a teleport to The Vestibule at A1. You arrive from the King's Palace via the pit there to B1 and the elevator is at C1. A blue lockpick opens most locked doors here. There are many square rooms arranged regularly around this area. Some have one way doors which can be a bind as they force you to drop through a trapdoor when you leave.
The central room contains two teleports. One from The Great Corridor is at H8 and one on the opposite side of the room, I9, leads to the Lava Cellar. This is the way you will return after falling through a trapdoor. To leave this room and enter the area proper, cast Detect facing the south wall at H9 and you'll find a secret door. Stairs to The Thieves' Den, go down from C8.
One NPC at N16 tells you that this is the lowest level of Cleowyn's Palace but merely the beginning of the dungeon proper. We still have a long way to go ...
The Lava Cellar
With the traps in the King's Domicile, you will get very familiar with the routes through this area. You can also reach it by teleport from the King's Domicile, arriving at F16 and returning that way after falling through a trapdoor.
You'll learn from one NPC that the only way to get out of this basement area is through the lava field. It is deadly to touch (I didn't test this out!) and its great heat will sap your strength. Another says there is a short cut through the lava field. If you can find the correct key, you'll be able to use the short cut. The key will also lead you to riches. (The key needed is the Lava Key which you find after a fight at O7. This is reached by passing through a series of one-way doors and having a lot of fights on the way.)
The Lava Key opens several doors. There is a Fountain of Hot Ice to restore your health at J2 behind the door at J3. It also unlocks doors at L7 and K8. K8 leads to the short cut (the 'long cut' is via a door at M8). Visit L8 too for a lucrative fight with wyverns which is the one the NPC was talking about.
A teleport to The Pit Bottom is at P1. To enter the bottom left corner, you'll need to use the teleport at G7 to get to A2. Several one way routes (doors and walls) round here. The bottom right area, which is large but mostly empty, can only be dropped into from the King's Domicile. One NPC tells you there is a teleport to the top somewhere round here. Another says the pillow labyrinths are deep in the dungeon. The labyrinth is the hollow part of the lava.
Pit Bottom
Once strong enough, you can drop into here from the pit in The Mines. But you can also get here by teleport from The Lava Cellar, arriving at D1. You'll need the Lava Key to unlock the door at C4 and a Fountain of Restoration restores your health at H8. Other than that, not much here. One NPC tells you to find the Fountain of Tranquillity if you are battle weary, and if you can. Another says a thief told him of a wondrous world of four seasons deep in the heart of the dungeon. There's something to look forward to! Or not, as it turns out ...
The Thieves' Den
This is reached in two ways; from a door in the hidden area in The Mines, or from the King's Domicile. It leads back to the latter. A sign at F15 welcomes you to The Thieves' Den and not only is it full of various thieves but also magic users, undead, odd wyverns, polar bears and many other creatures. Some encounters have four different groups of monsters! An exit at J14 leads back to the Inn. Later you'll find stairs down at E15 and N14 which both lead to the The Labyrinth I.
There are secret doors to find using Detect and also walls to walk through. This held me up for several days. I knew from True Seeing and Read Tracks that there was more to explore but couldn't find it. Detect didn't help. All you need to do is walk through the wall at M16 - simple when you know how! Then through another at P14. Thanks to Maureen Barton for helping me out there.
There are a series of hidden rooms along the top, each accessed by walk-through walls. Tough fights in here but good treasure too, especially at P8 (I got a sensor prism, beastly shield and bow of sorrow) and P9 (a cabinet holds various scrolls and potions plus there is 15000GP in a sack). P11 isn't bad either (a purple lockpick and 1250GP in my case)
If you come to a dead end, start backtracking, checking walls using Detect and trying to walk through them. Sometimes you'll find a hidden door which is locked too. Use a lockpick - I struck to my trusty blue lockpick. To return, sometimes you walk back through the wall, other times a door appears. A blue lockpick is the only one that will unlock the door at A1 - behind it is Sinestra's Fountain which makes you feel more healthy and experienced when you drink from it.
Back on The Soldiers' Quarters, an NPC told us we could learn new skills in the dungeon and this is the place. Thieves will teach you various skills ... Detect at E5, Bard Skill at J9, use of staves at the Staff Training Centre (ho, ho) at C2, Archery at A7, Lockpick at C5, Fencing Training Centre at H13 and The Axe and Club Training Centre at M6. The Thieves Infirmary where all your wounds will be cured is at N8.
There is a secret door (locked, use your blue lockpick) at N12 and a tough fight beyond. The north wall here also has a locked secret door and behind THAT is oodles of treasure - well, 5000GP, plus several goodies and the Thieves' Key. Very handy. The locked door at P15 opens using it. Behind a door at K10 a wise old thief tells you some useful tales, you're told, but what use they are I have no idea! If you return, he is asleep and can't be woken.