The Necromancy of Thay key is an item you've got to hunt down in Baldur's Gate 3 if you want to open the mysterious dark magic tome you find in the apothecary's cellar in the Blighted Village. To get to the book itself, you've got to jump through all sorts of hoops, like opening a secret cellar door, tricking a magical talking mirror, and disabling some traps around the book itself.
You've also got to open the barred door in front of the book—you can grab the Rusted Key to do this from a shelf in the laboratory's westernmost room. This is right by the lever that lowers the wall, letting you back into the previous area, so it's hard to miss. Even when you have the book, you still have to unlock it, and ultimately decide whether you want to destroy it or take its power. Here's where to find the Necromancy of Thay key, plus what choices you can make.
How to open the Necromancy of Thay
To open and read the Necromancy of Thay, you'll need an item called the Dark Amethyst to unlock it. Luckily, there's one pretty close by in the Whispering Depths underneath the Blighted Village, but you'll need to brave a bunch of Phase Spiders to find it. Here's how to get the Dark Amethyst and open the Necromancy of Thay:
- Examine the well in the centre of the Blighted Village and either use Investigation or throw in a coin, before climbing down into the nest.
- While you can fight through the nest, Phase Spiders are tough opponents, so your best bet is to hide and sneak or even use invisibility if you have it.
- From the bottom of the well, head northwest until you find a skeleton and an Ettercap patrolling on a higher platform. Once its back is turned, sneak past it into the main nest with the Phase Spider Matriarch and a giant hole.
- You'll spot the Dark Amethyst on the far edge of the hole. Here, I use a scroll of Feather Fall, wait for the spiders to look away, then jump down, grab it, and then sneak away. Even if the spiders spot you, it isn't too hard to disappear again depending on where they warp to.
Necromancy of Thay choices
Once you've got the Dark Amethyst, you can open the book at any time by examining it in your inventory. Ultimately, you have three choices surrounding the book:
- Read it yourself: To learn the Necromancy of Thay's secrets, you'll have to pass three Wisdom skill checks of escalating difficulty—10, 15, and 20—as you turn each page in the book. If you succeed at all three you'll get the Forbidden Knowledge trait, which gives you a permanent +1 to all Wisdom saving throws and ability checks, plus the Speak with Dead ability. You'll also be able to finish reading the book later in the game for some pretty wild bonuses.
- Give it to Astarion: Once opened, you can give the book to Astarion. He'll approve of this and look through the book briefly before holding onto it. Considering this a tome of Necromancy, it presumably tells him something important, but there are no immediate consequences.
- Destroy it: If you drop the book and use Shadowheart's Guiding Bolt spell, you can destroy the Necromancy of Thay, though I wouldn't advise this. Doing so will cause three very tough Shadow enemies to spawn and without a strong party, you'll die pretty quick. These Shadows are highly resistant to physical attacks and fighting them is just generally a bad time. The only real plus side to this is that you don't need to get the Dark Amethyst to do it.
- Hold onto it: There's no rush to open the book once you have the key, so you could always hold onto it until you are strong enough to beat the three Shadows. You'll also get a way to read the Necromancy of Thay fully later in the game, so you can always wait till then, though you'll still be able to read more once you have the right item regardless
How to finish reading the Necromancy of Thay
To finish reading the Necromancy of Thay and complete the quest, you're going to need to read another specific book first: The Tharciate Codex. You can't get this until act 3 when you reach the Lower City of Baldur's Gate. Below Sorcerous Sundries and Ramazith's Tower, you'll find the Sorcerous Vault where the wizard Lorroakan keeps his prized treasures. The easiest way into the vault is through the tower itself, which you can get into via the Nightsong quest and telling Lorroakan you have information. Once inside, jump down the floating furniture to the lower levels, then hit the button labelled "Vault" on the outer rim of the tower.
While there are lots of valuable items here, you'll want to keep heading through doors, past the portal, until you reach a door labelled Ramazith. Unlock this to be faced with three other named doors; Elminster, Silverhand, and Karsus. The book you want is behind the Elminster door and you have to complete a series of steps to unlock it. While being very wary of traps, you need to:
- Walk through the Silverhand door
- Walk through the Abjuration door
- Turn around and walk through the Wish door
- Pull the lever inside to unlock the Elminster Vault
Once you've liberated the book from its display case, you'll have to read it to gain the knowledge required to successfully finish reading the Necromancy of Thay, but it'll also curse you for -5 constitution. Don't worry, though, this is reversible. Read the Necromancy of Thay again and pass a difficulty 20 Wisdom check and you'll get the Danse Macabre bound spell, which lets you summon six ghouls once every long rest.
In terms of fixing the Tharciate curse, use the Remove Curse spell, and it'll be converted to Tharciate Vigor, which gives you 20 temporary hitpoints once every long rest—pretty good, am I right?
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