The vast subterranean domain of the legendary archmage Concelhaut contains the labs of his four apprentices and the archmage's own quarters. Forgotten tomes of lore line the numerous bookcases across Concelhaut's domain, filled with glyphs, blank pages, and the occasional usable piece of information.
Points of interest
Immediately after you enter, a thrall assassin invites you to visit one of the apprentices of the archmage.
You can visit the labs of four apprentices: Tanoss, Pelden, Sabel, and Uriaki. The door to Concelhaut's room is locked, to open it, you need four notes that give hints how to answer a riddle. These can be retrieved from the apprentices, you can either kill all of them, or follow Tanoss' offer to kill the other three to get his. Uriaki will also offer her key if you kill Tanoss instead. There are trapped and locked chests in the labs, and a hidden floor plate in Uriaki's lab. If you come back to Tanoss after killing Concelhaut, it will attack you. If you instead sided with Uriaki, she will have a little extra dialogue but wiill otherwise stay peacefull. Unfortunatelly, she will not leave the tower and she and her minions have very high sneaking detection, so you might have to murder her if you want to get the loot in her lab (including 3 durgan iron ingots in hidden tile)
Pelden works on guls and his ghastly laboratory is testament to that. However, he is one of the easiest apprentices to kill, as you can surround him before talking and take him out in the first seconds of the fight. He drops Pelden's note.
Sabel's lab and her vat of molten metal offer no special interactions; the closed door in her quarters leads to a chamber full of animated skeletons. She is a difficult fight due to the sheer amount of supporting mages with bounding bolts, which can wreak havoc if your party fails Reflex checks (and it likes to do so). Grab Sabel's research notes from her desk.
When you have read all four apprentices' notes, you can answer the questions at the door to Concelhaut's office (if you haven't read all notes, the correct answers will not appear in the dialogue options):
(first defense): "A warded mind."
(which weakness is deadliest): "Pride."
(most critical to powerful spellwork): "Malleability - it can be shaped into any spell."
You can leave the area towards the lower right of the map by pulling the lever on a column which opens the wall. Some not so easy enemies here. Exit is a shortcut to the right edge of the Crägholdt Bluffs map.
The game advances one turn after defeating Commander Baelorin and after reading the fourth note and two turns after defeating Concelhaut. Experience total 25650 xp for the quest, additional xp for several Bestiary entries (Lich, Animated Weapon, Void Seer, Steelspine Magus) and possibly a few thousand xp for disabled traps and locks.
At the staircase and inside Concelhaut's room, there are bookshelves that yield random loot, some based on stats. "Failing" to search any bookshelf will advance time by 4 hours and add fatigue. Successfully searching or failing to search a bookshelf twice will cause it to no longer be searchable.
Upon searching, you will get one of the following at random (non-repeating). Some of these checks have conditions and are not considered as part of the random "roll" if you don't meet them.
The first bookshelf is next to the entrance staircase, and the second and third are on the right and left hand side of Concelhaut's Chambers respectively.
Near the back of one shelf you find a tome covered in strange symbols. It doesn't look like much at first, but you eventually recognize the symbols as incantations and the book and a grimoire.
Haven't already looted a Battle-worn Grimoire from one of the other shelves
You find an old book on one of the top shelves. It's covered in dust, so you almost miss it. But as you brush it off and flip through the pages, you recognize it as an early copy of "The Iroccian Calendar."
There is also a treasure chamber. The door is locked with level 8, and when you open it, it will trigger a lightning chain trap that can't be defused, but you can avoid being hit if you open the door carefully from the right side. Also you should take care not to be seen by the flying skulls (Void Seers) when you enter, or they will turn hostile. Inside are two large crates, the right one is trapped with level 10 (Malignant Cloud Trap) and locked with level 8, it contains The Last Tower (large shield), an Iridescent Scarab Figurine and 1044 . The left crate is trapped with level 14 (Storm of Fire Trap) and locked with level 12, it contains an Exceptional Battle axe, 5x Sapphire, 4x Ruby, 3x Emerald, 3x Topaz, 3x Diamond, and 1854 . There are also vases that contain 5x Pearl, 5x Opal, 5x Adra, and 17x Adra Bán.
There is an easily missed hidden stash under a tile just southwest of Concelhaut's desk which requires 14 or 15 mechanics to spot, which contains some potions and two rubies.