Location: From BM secretary 2w max s, wait till Theddin comes and say him “explore” after long conversation; then go down. Though, dwarves will not allow evil-aligner to enter, but there is another entrance (heavydoor) from outside BM - decent str needed to open it though.

Strategy: Zone is mudlled; at each repop the exits from all 100 rooms randomly change. But it is not true random: you will never be blocked in some rooms after repop because between each two rooms in these mines after each repop always is one way, and one only (exception - spiders' lair with secret exit). Spiders pop in their lair, and a while later they start to move randomly in the maze. They are about level 16, so they don't hit too hard and have an average amount of hps.
Main danger of these spiders is that they can trap you in their web! This does not happen instantly, though. First you will get a message that the spiders start producing the web (it is not dangerous). Then you will see the second message:

A great, dark spider quickly begins to weave a tight, sticky web around your body!

Flee if you are solo, or be ready to flee if in group. Then you will see third:

A great, dark spider burdens your movement wrapping you layer after layer!

Flee after that! and spam around until you receive this message:

After some struggle you remove the last web on you.

If you don't flee, soon you will see message containing words “faster and faster around you”. After this (fourth) message you will not be able to flee anymore - it is your last chance to narrate about your slow death in the cocoon. After fifth message you will become cocooned - that means you must wait for death (about half-hour rl) or wait for someone to come and free you. Inside the cocoon you will not be able to do anything, even check your inventory or narrate. Though, after the last change you can tell from inside coccoon.

If multiple spiders are engaged to you, can they cocoon you that many times faster? I've always been afraid to find out by, for instance, quaking a room with 3 or so of these spiders in it. -Belamir

Also, if you sleep in mines, spiders will cocoon you instantly, without any message, so NEVER sleep there!

So: If you are a mage, always keep stored 2 fireballs (solo spider dies in 2 fireballs + 1-2 bolts). Warrior should have maxOB equipment and be in aggressive mood - just fight some/spam to remove webs. Same goes for thieves: spiders see sneakers, so backstab is impossible. On low hps spiders spamflee, so be ready. After finishing all spiders in the maze, go to their lair (s from large sign, always same exits). There are usually 2-3 spiders in the same room, so for mage will be good to store some earthquakes, but hitter must lure spiders outside one by one.
After killing them, get key from one of the corpses, open cover down from main room in their lair, turn swim on and jump down. You must have at least 60-80% swim for swimming underwater. When you notice a glinting item, type reveal key. The spider's key is for the door before the chest (in north-western part of mines, some N of mineshaft up), glinting key is for the chest.

Level: Hero mage with store/warrior/thief with good bow/cleric with blind; also needed ultra-stable link or(/and) labfriends ;)

Loads: Steel-shafted mattock, metal wall shield, amethyst, some gold.

Mobs unique to the zone:

• A great, dark spider