BG3: How to Get & Open the Necromancy of Thay

The Necromancy of Thay grants a permanent buff and the Speak with Dead spell — but most players get stuck finding the book, the hidden key, or the gem that opens it. Here’s the full Act 1 process.

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Short Answer

The Necromancy of Thay is in the Apothecary’s cellar in the Blighted Village. Drop through the hatch behind the counter, pull the hidden lever behind the crates to open a passage, answer the Ornate Mirror, and grab the key to reach the book behind a trapped gate. To open it, fetch the Dark Amethyst from the bottom of the well in the Whispering Depths (near the Phase Spider Matriarch), insert it, and pass the DC 10, 15, and 20 Wisdom saving throws to gain the Forbidden Knowledge passive (+1 Wisdom saving throws and ability checks) and Speak with Dead.

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Key Takeaways

• Book location: Apothecary’s cellar, Blighted Village — hatch behind the counter.
• Pull the hidden lever behind the crates, then answer the Ornate Mirror to open the way.
• Grab the scroll of Summon Quasit from the casket on the way (good for Gale).
• Ungroup your party — there’s a trap right in front of the book’s gate.
• The Dark Amethyst key-gem is at the bottom of the Whispering Depths well.
• Pass DC 10/15/20 Wisdom saves for Forbidden Knowledge and Speak with Dead.

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Where Is the Necromancy of Thay?

It’s in the Apothecary’s cellar in the Blighted Village. Fast-travel to the Blighted Village waypoint, enter the Apothecary’s house behind it, and use the hatch behind the counter to drop into the cellar.

Inside, pull the hidden lever behind the crates to reveal a passage. Follow the alleyway to a casket holding the Scroll of Summon Quasit (worth picking up), then reach the Ornate Mirror and answer its questions to turn it into a doorway. Take the key from the small room on the right, then open the locked gate — but ungroup your party first, because there’s a trap directly in front of the gate. Grab the book and store it.

How Do You Open the Book?

You need a Dark Amethyst. Leave the cellar (pull the lever to exit) and return to the Blighted Village waypoint, where there’s a well right beside it. Investigate it and use the bucket rope to descend into the Whispering Depths.

At the very bottom of the spider nest, near the glowing green pit by the Phase Spider Matriarch, grab the Dark Amethyst (fight or sneak past the spiders). Open your inventory, read the book to insert the gem, and pass the DC 10, 15, and 20 Wisdom saving throws. Success unlocks Speak with Dead and the permanent Forbidden Knowledge passive (+1 Wisdom saving throws and ability checks).

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FAQ

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

In the Apothecary’s cellar beneath the Blighted Village — enter via the hatch behind the counter, pull the hidden lever behind the crates, and pass through the Ornate Mirror.

Where is the Dark Amethyst?

At the bottom of the well next to the Blighted Village waypoint, down in the Whispering Depths near the Phase Spider Matriarch’s glowing green pit.

What do you get for reading the Necromancy of Thay?

Speak with Dead (talk to humanoid corpses for clues) and the Forbidden Knowledge passive — a permanent +1 to Wisdom saving throws and ability checks.

Do you need to fight the Phase Spider Matriarch?

You can fight or sneak past the spiders to reach the Dark Amethyst — killing the Matriarch isn’t strictly required to grab the gem.

What happens if you fail the Wisdom checks?

Failing the DC 10/15/20 saves can leave you unable to safely read the book that attempt. Boost Wisdom or use guidance/advantage before reading to pass cleanly.

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Related Guides

• Necromancy of Thay & Tharchiate Codex: Full Guide — the complete Act 1–3 questline in one place.
• Tharchiate Codex Location & Vault Puzzle (Act 3) — finish the quest and unlock Danse Macabre.

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Sources

• How to Get & Open Necromancy of Thay in Baldur’s Gate 3 (Full Guide) — original video walkthrough by Fusion Thunder.