Before trying that tremendous quest, be sure that you are loaded with magical fruits. I would recommend at least a full bag of Ironskin fruit, another of Psi lemons, as well as some Free Action grapes.

When you are ready, go to Faria's passage and try a certain combination of numbers (I won't tell more) and hope that the quest in opened. If it is, you will have a message that you have found the entrance of the Illithid's lair, and ask you if you want to enter that place... Think twice as when in, you can't get back, you will have to find another exit, and you can't rest down there.

So you are into that dark place, alone and scared, in A. This map might not be 100% correct, there are some rooms I don't exactly remember of...

You don't need to prepare for fight, as this first room is empty, save for some dead bodies that you can look at. Save your spells for further use, you'll need them! You can look at some strange drawings in B, then take a door at North. You will enter a room where some drunk Mind Flayer lies here and there, you can try to talk to one of them in C, but you will not have much information. Then go in D and meet two Mind Flayers, Tol-Vek and Kezriss. Listen carefully to what they say, as the will explain waht must be done under there...

Go close to Northern exit and spell up, as you will fight in E (each time you cross that central room), against 1-3 Mind Flayers or 1 Intellect Devourer. The Mind Flayers will try to eat your brain (I don't know what it makes though, as they never succeeded), they will charm you if ever they hit, otherwise they use Id Insinuation. The most recommend defensive spells are Ironskin, Free action, Mind Blank and Tower of Iron Will. Otherwise you can Jam Psionics... But this has some drawbacks. Intellect Devourers are +3 weapons to hit, and even if you have such weapon, each blow makes only 1 HP damage. But you can use Id Insinuation and Disentegrate, it works fine... If you don't Jam Psionics! That's why you need plenty of Psi lemons to restire psi.

You have 3 exits to that room. I recommend that you first go North, where you'll fight 4 Mind Flayer guards in F. They will drop a pink and grey key if you shaken them hard enough. Then go back in E (another fight) and take East exit, this time. There are some wandering slaves and guards in this room, you can sneak by them (Kezriss might appear and help you), or just kill them so they won't bother you anymore.

Enter a strange laboratory in G where you will find the Duarch Poliss. He doesn't like to be interrupted in his work and will call some guards to kick you out, but if you show who's the boss he will quicky drop some strange piece of something. Pick it for further use... You can also pick some kind of telepathic orbin H, it's the only place where you can pick one.

Go south and open the door in I, using the key that you got in F, then you will hear some conversation coming from next room. If you view the door in J, a group of Mind Flayers will try to persuade you that it's very impolite to hear at doors. Among them are the Great Patriach and the Inquisitor, who will kindly drop a grey and blue key that is similar to the one opening Dariya's secret passage. Go to K and view the safe there (you can't bash it or pick the lock otherwise), it will open and you'll get 6.666 XPS, 20.000 CPs and another strange piece of something.

Head to L, crossing E (another fight, of course), and meet some slaves there. You will also meet a strange character in the name of Dolaris, who owns a third strange piece of something. If you talk properly to her, you can convince her to give you the piece, otherwise you can just bash her. Anyway that will happen of you don't talk to her in the proper way, but beware, she seems to be 100% magic-resistant and will use plenty of spells against you. Fortunatley you have a strong sword arm...

Pick that last piece of something and go back to E (fight), then F (no more fight) and N. You can also look at all the telepathic orbs that lies in M, and listen to the Mind Flayers's thoughts. There seems to be a door in N, and if you look carefully you can see some spot on the wall that have the same shape as your 3 strange pieces of something... Be ready for a tough fight, then put the pieces on the proper spots, and a door will open...

As soon as you enter in O, that seems to be the throne room, you are assaulted by the Primarch and his guards (4 Mind Flayers and a Intellect Devourer). If you survive that, the Primarch will drop a black key, that opens the door leading to P, where you find a elder brain under construction. If you do the right thing, you will have a 6.666 XPs reward and Kezriss will appear to thank you and to give you a purple key that open the upper door, leading to a well guarded tomb... Don't forget to pick the treasure in Q (20.000 CPs and a wand of Magic Missiles).

If you are courageous enough, open the last door and enter the tomb where you will be welcomed by 2 Earth Drakes in R. Then look at the throne in S, where lies Promere's dead remains, fight a pair of Magma Golems, and maybe pick the Promere's hammer (It's a UNIQUE, so it might not be available). Then look in T, and you will find a very interesting suit of armor.

Now this is time to get out of there. The exit is in V, and you will have to move the proper lever in U. Of course, you will have a fight in E...

Maybe there is a litlle more to do in here, as Kezriss last said that he should meet me again, and also I still have the mysterious orb that I picked in H...