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Necromancy of Thay & Tharchiate Codex: Full Guide (Act 1-3) — Baldur's Gate 3 video guide thumbnail
Baldur's Gate 3 Guide 6 min read

BG3 Necromancy of Thay & Tharchiate Codex: Full Guide

Full Baldur's Gate 3 guide to the Necromancy of Thay and Tharchiate Codex — unlock Forbidden Knowledge, Speak with Dead, +20 temp HP, and the Danse Macabre ghoul army.

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Quick Answer

The Necromancy of Thay is hidden in the Apothecary's cellar in the Blighted Village (Act 1) — pull the lever behind the crates, answer the Ornate Mirror, grab the key, then unlock the book with the Dark Amethyst from the Whispering Depths well and pass the DC 10/15/20 Wisdom saves for Forbidden Knowledge (+1 Wisdom saves) and Speak with Dead. In Act 3, take the Tharchiate Codex from the Sorcerous Sundries vault (Silverhand → Evocation → Wish doors), cure the Tharchiate Withering curse with Remove Curse for a permanent +20 temp HP, then read the book to learn Danse Macabre.

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The Necromancy of Thay is one of Baldur’s Gate 3’s most powerful permanent rewards, and it works for any class. This guide covers the whole questline end to end: finding and opening the book in Act 1, then claiming the Tharchiate Codex in Act 3 to unlock the Danse Macabre ghoul army.

Short Answer

The Necromancy of Thay is hidden in the Apothecary’s cellar in the Blighted Village (Act 1). Pull the hidden lever behind the crates, answer the Ornate Mirror, grab the key, and unlock the book with the Dark Amethyst from the well in the Whispering Depths. Passing the DC 10, 15, and 20 Wisdom saving throws grants the Forbidden Knowledge passive (+1 Wisdom saving throws and ability checks) and Speak with Dead. In Act 3, take the Tharchiate Codex from the Sorcerous Sundries vault, cure the Tharchiate Withering curse with Remove Curse for a permanent +20 temporary HP after every long rest, then read the book to learn Danse Macabre.

Key Takeaways

  • The book is in the Apothecary’s cellar in the Blighted Village — reached via a hatch behind the counter.
  • Opening it needs a Dark Amethyst, found at the bottom of the Whispering Depths near the Phase Spider Matriarch.
  • Reading it requires passing DC 10, 15, and 20 Wisdom saves → Forbidden Knowledge (+1 Wisdom saves/checks) and Speak with Dead.
  • The Tharchiate Codex (Act 3) is locked behind the Sorcerous Sundries vault puzzle: Silverhand → Evocation → Wish doors.
  • Reading the Codex inflicts Tharchiate Withering (-5 Constitution); cure it with Remove Curse for a permanent +20 temp HP per long rest (Tharchiate Vigor).
  • Finishing the quest unlocks Danse Macabre — summon up to 4 ghouls (5 as a Necromancer).

Where Do You Find the Necromancy of Thay? (Act 1)

The book is in the Apothecary’s cellar beneath the Blighted Village. Fast-travel to the Blighted Village waypoint and head to the Apothecary’s house behind it. Look behind the counter for a hatch leading down to the cellar.

Inside the cellar, pull the hidden lever behind the crates to reveal a passage. Follow the alleyway to a casket on the right that holds the Scroll of Summon Quasit — worth grabbing (Gale can learn it). Continue to the Ornate Mirror and answer its questions to open the way (full answers below). Then grab the key from the small room/kitchen on the right and open the locked gate.

Watch the floor: there’s a trap right in front of the gate. Ungroup your party so they don’t follow you onto it, then move through carefully and take the book.

How Do You Open the Necromancy of Thay?

You need a Dark Amethyst to unlock the book. It’s close by, at the bottom of the Whispering Depths. Return to the Blighted Village waypoint and investigate the well beside it — use the bucket rope to descend.

At the very bottom of the spider nest, near the glowing green pit by the Phase Spider Matriarch, you’ll find the Dark Amethyst. Fight or sneak past the spiders, grab the gem, then open your inventory and read the book — it places the amethyst in the book’s “mouth” to unlock it. Pass the DC 10, 15, and 20 Wisdom saving throws to gain Speak with Dead and the Forbidden Knowledge passive (+1 Wisdom saving throws and ability checks).

Close-up of the Necromancy of Thay tome in Baldur's Gate 3 — a skull-faced book with glowing eyes and an oval recess in its mouth for the Dark Amethyst.
The Necromancy of Thay is locked tight — an oval recess in the cover's "mouth" takes the Dark Amethyst.

Where Is the Tharchiate Codex? (Act 3)

The Tharchiate Codex is inside the Sorcerous Sundries vault in the Lower City. Go to Sorcerous Sundries (the large magic shop in the center of the map) and head to the second floor. On the left is a locked door to the Tome Monger’s office — use Invisibility to lockpick it unseen, or distract the guard, then slip in and close the door.

Inside, interact with the closed book on the bookcase to open a portal to the vault. From the hub, take the oak door and break down the locked door past the hallway (mind the weak traps). Then work the door puzzle:

StepDoorResult
1SilverhandStarts the sequence
2EvocationContinues toward the lever
3WishReach the lever — pull it to open the Elminster vault
4Back to start → Gate → IllusionOpens the lit door to the Elminster vault

In the Elminster vault, smash the display case to take the Codex.

How Do You Finish the Quest and Get Danse Macabre?

Give the Codex to whoever read the Necromancy of Thay (or your main character) — but expect a curse. Reading the Codex inflicts Tharchiate Withering (-5 Constitution). Cure it with the Remove Curse spell (Shadowheart, as a Cleric, can cast it) to convert it into Tharchiate Vigor — a permanent +20 temporary HP after every long rest.

With the curse gone, read the Necromancy of Thay again and pass a final DC 20 Wisdom save to learn Danse Macabre: summon up to 4 ghouls to fight for you (5 if you’re a Necromancer), rechargeable on every long rest.

FAQ

Where is the Necromancy of Thay in Baldur’s Gate 3?

In the Apothecary’s cellar beneath the Blighted Village in Act 1 — drop through the hatch behind the counter, pull the hidden lever, answer the Ornate Mirror, and grab the book behind the trapped gate.

What are the Ornate Mirror answers?

Tell it your name; say you’re an ally of your masters; “A foolish lass may die a thousand deaths”; “to clean a wound”; and “I look for whatever spell will rip me from this worm in my head.” The mirror then becomes a doorway. (Auto-caption wording — verify in-game.)

How do you open the Necromancy of Thay?

Place a Dark Amethyst (from the Whispering Depths well, near the Phase Spider Matriarch) into the book, then pass DC 10, 15, and 20 Wisdom saving throws to gain Speak with Dead and the Forbidden Knowledge passive.

Where is the Tharchiate Codex?

In the Sorcerous Sundries vault in Act 3. Enter through the Tome Monger’s office on the second floor, then solve the door puzzle (Silverhand → Evocation → Wish, then Gate → Illusion) to reach the Elminster vault.

How do you cure the Tharchiate Withering curse?

Cast Remove Curse (e.g. with Shadowheart) on the cursed character. This turns the -5 Constitution debuff into Tharchiate Vigor: a permanent +20 temporary HP after every long rest.

How many ghouls does Danse Macabre summon?

Up to 4 ghouls for most classes, or 5 if your character is a Necromancer. It recharges on a long rest.

Sources

Fusion Thunder
Founder & Editor

I'm Fusion Thunder, the founder of Beyond Max Level. I'm a lifelong gamer and content creator who doesn't just play games — I like to push them to their absolute limits. This site is the written extension of my YouTube channel, @BeyondMaxLevel, where I break down the open-world epics and big RPGs worth going deep on into clear, no-fluff guides you can actually follow.

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