BG3 Necromancy of Thay Book Guide: How to Use It, Unlock the Forbidden Tome, and Get the Tharciate Codex

What the Necromancy of Thay Book Actually Does in BG3

So you wanna use the Necromancy of Thay book in Baldur's Gate 3? Congrats, you just found one of Act 1's creepiest optional rewards. This forbidden tome is hiding in the Blighted Village, and it kicks off a puzzle, a saving throw mini-game, and a payoff that doesn't show up until way later in Act 3.

I still remember my first time opening it. My character started hearing whispers, and I honestly couldn't tell if I was about to get a sick spell or a nasty curse. Turns out it's a little of both, depending on how you play it.

Here's the quick version: the book gives you a permanent buff, and if you finish reading it, you eventually unlock the Tharciate Codex, which leads to a free Feat. Let's break down every step.

Where to Find the Necromancy of Thay Book

Before you can use the Necromancy of Thay book, you gotta find it first. It's inside the Blighted Village, in the apothecary's basement.

Step-by-Step: Getting to the Book

1. Enter the Blighted Village in Act 1, west of the Emerald Grove.
2. Find the apothecary's house near the center of the village. It's the building with the locked door and the "Apothecary" sign.
3. Pick the lock or break in. The lock is around DC 15, so bring a rogue or use Knock.
4. Inside, look for a trapdoor or hatch leading to the basement. It's behind a bookshelf or in a back room.
5. Go down. You'll find a locked and trapped chest in the basement.
6. Disarm the trap (Perception check to spot it, then Sleight of Hand to disarm). If you fail, you'll take damage and possibly alert enemies.
7. Open the chest. Inside is the Necromancy of Thay book, along with some other loot.

Quick heads-up: there are also Whispering Depths nearby, but the book itself is in the apothecary basement, not the spider cave. Don't mix those two up like I did on my first run.

How to Use the Necromancy of Thay Book: The Whisper Puzzle

Once you've got the book, you can't just read it like a normal item. It's a multi-stage interaction that needs specific items and successful ability checks.

What You Need Before Reading

You need three key items to fully unlock the book:

• The Dark Amethyst – found in the Whispering Depths, on a spider egg sac or near the Phase Spider Matriarch.
• The Necromancy of Thay – the book itself.
• A character with decent Intelligence or Wisdom – because you'll be making saving throws.

Actually, you only need the Dark Amethyst to start the process. The other "items" are your party members' brains.

Step-by-Step: Reading the Book

1. Get the Dark Amethyst. Kill the Phase Spider Matriarch in the Whispering Depths, or loot the gem from the nearby egg clusters. It's a purple gem.
2. Select the Necromancy of Thay in your inventory. Right-click and choose "Read."
3. A dialogue window opens with whispering text. You'll be asked to insert the Dark Amethyst into the book's cover.
4. Do it. The book opens, and you're presented with three whispering passages.
5. Each passage requires a Wisdom saving throw (DC 15) or an Intelligence check depending on the dialogue option. You need to succeed on all three to fully read the book.
6. If you fail a save, you take psychic damage and the book closes. You can try again after a long rest.
7. Once you pass all three, the book is fully read. You gain the Forbidden Knowledge buff, which gives you +1 to all saving throws and advantage on saving throws against being frightened.

That's the core of how to use the Necromancy of Thay book. It isn't a one-and-done thing. You gotta commit.

Class and Companion Interactions

Not every class handles the book the same way. Here's what changes:

• Wizard: Gets unique dialogue options. You can use Arcana to bypass one of the saving throws. This is the easiest class to read the book with.
• Warlock: Gets advantage on the saving throws if you have the Great Old One patron. The whispers feel "familiar."
• Cleric or Paladin: You can choose to destroy the book instead of reading it. This gives you a different outcome and some approval from certain companions.
• Rogue: No special dialogue, but you can sell the book for a decent amount of gold if you don't care about the reward.
• Companions: If you give the book to Astarion, he'll be tempted to read it. Gale will warn you against it. Shadowheart is indifferent. Wyll disapproves if you keep it.

You can also have a companion read it for you. Just put the book in their inventory and have them interact with it. Their saving throws apply.

The Tharciate Codex Reward: What You Actually Get

The Tharciate Codex is the final reward for fully reading the Necromancy of Thay. But here's the catch: you don't get it in Act 1.

How to Get the Tharciate Codex

1. Fully read the Necromancy of Thay in Act 1. You must pass all three saving throws.
2. Keep the book in your inventory. Do not sell it or destroy it.
3. Progress to Act 3. Specifically, reach the Lower City of Baldur's Gate.
4. Find the Sorcerous Sundries bookstore. It's in the Lower City, near the center.
5. Inside, look for a locked vault or a specific bookshelf in the back. You'll need to pass a Perception check to spot it.
6. Interact with the Tharciate Codex (it's a separate book that appears once you've read the Necromancy of Thay).
7. Reading the Tharciate Codex grants you the Tharciate Codex permanent buff: +1 to all saving throws (stacks with Forbidden Knowledge) and immunity to being frightened.

Wait, that's not all. The real prize is that the Tharciate Codex unlocks a free Feat for your character. You can choose from a small list, including Resilient or War Caster. This is huge for builds that need an extra feat.

Why It's Worth It

The Necromancy of Thay is a long-term investment. You spend Act 1 and Act 2 carrying a creepy book around, and then in Act 3 you get a free feat. That's better than most quest rewards.

Common Mistakes Players Make

I've watched a lot of people mess this up. Here are the big ones:

• Selling the book too early. If you sell the Necromancy of Thay, you can't get the Tharciate Codex. Keep it.
• Destroying the book. Some classes can destroy it. That's a valid roleplay choice, but you lose the reward.
• Failing the saving throws and giving up. You can retry after a long rest. Don't just walk away.
• Forgetting the Dark Amethyst. You can't read the book without it. Grab it from the Whispering Depths before you try.
• Not checking the Sorcerous Sundries vault. The Tharciate Codex doesn't just appear in your inventory. You have to find it in Act 3.
• Assuming any class can read it easily. Wizards have the easiest time. Other classes might need to burn inspiration or reload.

One more warning for new players: don't sleep on your saving throw gear before attempting the book. That DC 15 Wisdom save will humble you real quick if your character dumped Wisdom.

FAQ

Q: Can I read the Necromancy of Thay book with any class? A: Yes, but Wizards get an Arcana check to skip one saving throw. Warlocks with Great Old One get advantage. Everyone else just needs to pass the DC 15 Wisdom saves.

Q: What happens if I destroy the Necromancy of Thay? A: You lose access to the Tharciate Codex and the free feat. You might get some companion approval, but it isn't worth it mechanically.

Q: Do I need to keep the book after reading it? A: Yes. You must have the Necromancy of Thay in your inventory when you reach Act 3 to trigger the Tharciate Codex. Don't sell it.

Q: Is the Tharciate Codex worth the hassle? A: Absolutely. A free feat plus stacking saving throw bonuses is one of the best rewards in the game. Just don't forget where you put the book.