The Necromancy of Thay is a book that can be unlocked using a Dark Amethyst obtained in the Search the Cellar side quest in Baldur's Gate 3 (BG3). Read on to find out how to open the Necromancy of Thay, how to unlock the Ancient Tome, and how to do the Search the Cellar side quest!

Search the Cellar Details

Journal Entry
Unlock the Ancient Tome
Recommended Lvl	Lvl. 5
Rewards	・Forbidden Knowledge (Passive Feature) ・Speak with Dead Spell ・Summon Ghoul Spell
Related Quest	Search the Cellar
Location
Blighted Village

How to Get the Necromancy of Thay

	How to Get the Necromancy of Thay
1	Enter the Secret Hatch in the Tavern
2	Read the Healer's Log
3	Go Through the Hidden Passageway
4	Talk to the Ornate Mirror
5	Open the Iron Gate and Take the Book

Enter the Secret Hatch in the Tavern

There's a secret wooden hatch behind the counter in a tavern to the left of Blighted Village's main entrance. Open it and climb down to enter in what appears to be an apothecary's room.

Read the Healer's Log

There will be a book called Healer's Log which is sitting on a chemistry table near the curtains. Read the book as this will come in handy later on.

Go Through the Hidden Passageway

Destroy the boxes near the portrait of mountains to reveal a lever. Pull it down and a hidden passageway will open. Enter it and follow the path until you come across a field with wooden coffins.

Keep venturing onwards until you come across an ornate mirror.

Talk to the Ornate Mirror

Approach the ornate mirror and talk to it. It will ask you 5 questions that all need to be correctly answered in for the mirror to let you through. Choose the dialogue choices in the order below:

• Tell it your name.
• Yes an ally! I'm an ally of your master's.
• Szass Tam is a foul, wretched creature.
• I read a doctor's journal - he used balsam to clean a wound.
• I'd look for whatever spell will rid me of this worm in my head.

As you may have noticed, the answer on the balsam ointment question came from reading the book you found earlier in the Apothecary's room.

Failing to choose the correct answer will force the mirror to unleash a floating sphere that will emit flames that will damage you.

Open the Iron Gate and Take the Book

The Necromancy of Thay is locked behind an Iron Gate. Take the Rustic Key which can be found on a shelf beside a lever leading to the exit.

Use it on the Iron Gate to unlock it and grab the book. This will trigger a flamethrower trap but you won't have to worry as you'll enter turn-based mode and all you have to do is walk out of the room.

How to Open the Necromancy of Thay

	How to Open the Necromancy of Thay
1	Obtain a Dark Amethyst in Whispering Depths
2	Venture Through the Depths
3	Defeat the Phase Spider Matriarch
4	Pick Up the Dark Amethyst
5	Open and Read the Book
6	Travel to Baldur's Gate For the Last Page

Obtain a Dark Amethyst in Whispering Depths

To open the Necromancy of Thay, you need to unlock it with a Dark Amethyst which you can find in the Whispering Depths underneath the Blighted Village.

How to Enter the Whispering Depths

There are two ways to enter the depths: Roping down the well located at the town center of Blighted Village, or breaking down a weak wall in the basement of a house to the right of the village's main entrance.

Entrance	Map Image	Overworld
Well	View Full Image	View Full Image
Weak Wall (House)	View Full Image	View Full Image

Regardless of which entryway you choose, you'll still start your underground expedition at almost the exact same spot.

Venture Through the Depths

Keep on following the narrow path in the Whispering Depths while battling all the Phase Spiders and Ettercaps that you'll encounter along the way.

There are lots of climbable ledges around so use the High Ground to your advantage and get that sweet +2 bonus to your Ranged attack rolls.

Advantages of High Ground

Defeat the Phase Spider Matriarch

The Phase Spider Matriarch is a deadly mini-boss found at the end of the depths, and is deadly enough to wipe your whole party down with poisonous acids.

Despite her menacing offensive skills, her defense is lackluster and you can take her down easily by casting your most powerful spells from a safe distance.

A good method of fighting the Phase Spider Matriarch is to wait for it to land on the webbigs. These webbing are weak to fire and can easily be burned by fire attacks. This will make the Phase Spider to fall and take huge amounts of damage while inflicting Prone.

Be Wary of Phase Spider when on Low HP

When the Phase Spider is brought to critical levels of HP, the Phase Spider will go berserk. This can cause her to deal increased damage and be able to attack twice in a single turn. It is recommended to attempt to fight the Phase Mother Normally first before using the webbing to avoid this critical phase of the fight!

Pick Up the Dark Amethyst

Once the Matriarch is dead, climb down the vine to the left of the lair's entrance, and go to the giant hole in the middle. You'll find the Dark Amethyst lying on the ground, pick it up and exit the depths.

Open and Read the Book

Unlock the Necromancy of Thay by inserting the Dark Amethyst through a dialogue option upon interacting with it in your inventory.

You'll be rolling three Wisdom checks each time you turn a page. The first has a 10 DC, the second has 15 DC, and the last one has a 20 DC.

Rolling at least one successful check will reward you with the Forbidden Knowledge passive feature which gives a +1 bonus to Wisdom saving throws and Ability Checks.

What is Wisdom?

Failing a Check Gives You Debuffs

Failing one will give you the Whispers of Madness condition, and failing two gives you the Baleful Knowledge condition which both provides the same effect of imposing a disadvantage on all your future Wisdom checks.

How to Finish the Necromancy of Thay

Travel to Baldur's Gate For the Last Page

Head over to Sorcerous Sundries in Baldur's Gate. Once inside interact with the Clasped Book on the shelf to teleport to the Sorcerous Vault.

Go through the Oak Door and enter the succeeding doors in this order: Silverhand, Evocation, and Wish. Pull the lever in the final room and go back to the first room you came in, and enter the Elminister Vault.

Read the Tharchiate Codex which is required to finally finish the Necromancy of Thay book. Reading the final page requires a Wisdom check (20 DC) and you'll get the Speak with Dead and Summon Ghoul spells as your rewards.

Baldur's Gate 3 Related Guides

List of All Side Quests

Prologue Side Quests

All Prologue Side Quests
How to Free the Intellect Devourer	How to Free Shadowheart

Act 1 Side Quests

Druid's Grove Quests

Druid Grove Quests
How to Steal the Sacred Idol	Should You Save The Goblin Sazza?	How to Avoid Tiefling Pickpockets
Save the Refugees	How to Save Nadira	How to Save Mirkon
How to Save the First Druid Halsin	How to Open the Stone Slab	Request Help from Nettie
How to Investigate and Expose Kagha	Save Arabella	-

The Risen Road Quests

The Risen Road Quests
Find the Missing Shipment	How to Rescue the Grand Duke
Rescue the Trapped Man	How to Free Oskar Fevras

Blighted Village Quests

Blighted Village Quests
How to Beat the Goblins: Blighted Village	How to Open the Necromancy of Thay	How to Recruit the Ogres
How to Finish the Masterwork Weapon	That Barn: Avoid Killing Buthir	Rescue the Gnome and Stop the Windmill

Goblin Camp Quests

Goblin Camp Quests
How to Get Volo's Ersatz Eye	Defiled Temple Puzzle
Find the Nightsong	Ask the Goblin Priestess for Help

Nautiloid Crash Region Quests

Nautiloid Crash Region Quests
Dank Crypt Guide	The Dying Mind Flayer	Auntie Ethel Quest Guide
How to Get Owlbear Cub	Spiderling Nest Guide-	How to Open the Selunite Chest
How to Get Scratch	Should You Heal Pandirna	Underground Passage Guide

Underdark Quests

Underdark Quests
Arcane Tower Guide	Defeat the Duergar Intruders	Save the Grymforge Gnomes
Find the Adamantine Forge	Deliver Nere's Head	How to Find the Mushroom Picker
How to Cure the Poisoned Gnome	Help the Cursed Monk	Omeluum Location

Mountain Pass Quests

Mountain Pass Quests
Steal a Githyanki Egg	How to Beat Gremishkas	How to Access Guardian of Faith Room
Dawnmaster Puzzle Guide	Where to Find the Githyanki Creche	-

This section is currently under construction. Check back later for updates!

Act 2 Side Quests

Last Light Inn Quests

Last Light Inn Quests
Seek Protection from the Shadow Curse	Rescue the Tieflings	Rescue Wulbren
How to Lift the Shadow Curse: Where to Find Thaniel	Find Zevlor	Help He Who Was
Investigate the Selûnite Resistance	-	-

Gauntlet of Shar Quests

Gauntlet of Shar Quests
Gauntlet of Shar: All Trials and Umbral Gems	Kill Raphael's Old Enemy

Mind Flayer Colony Quests

Mind Flayer Colony Quests
How to Solve the Necrotic Laboratory

Act 3 Side Quests

Rivington Quests

Rivington Quests
Investigate the Suspicious Toys	Solve the Open Hand Temple Murders	Find the Missing Letters
How to Get to Wyrm's Rock Fortress	How to Find Dribbles the Clown	-

Lower City Quests

Lower City Quests
How to Get to the House of Hope	How to Get to Cazador's Palace	Rescue Orin's Victim
Aid the Underduke	How to Get to the House of Grief	Investigate the Murders