There are many secrets to be uncovered in Baldur's Gate 3, even in the game's opening act. One example is the Ancient Tome called Necromancy of Thay that you can discover in a Necromancer's lair hidden in a cellar in the Blighted Village. Exploration of the basement leads to uncovering more than a few secrets. This guide will go over how to claim the dark tome and its forbidden knowledge for yourself.
To find the Ancient Tome, you need to first find the secret passage. There is a note you can see that will give you the Search the Cellar quest or you can just stumble across it during your exploration of the village. Either way, once you find your way in, there are some puzzles between you and your prize.
How To Unlock The Ancient Tome
Once you have found the tome, you will notice it is locked, but you need something other than a key to get it open. The book has a slot on the front sealing it rather than a keyhole Coincidentally, also in the Blighted Village, there is a Dark Amethyst hidden in an area below the town that is the key to the forbidden knowledge. Go to the Well and interact with it, then climb down the rope to access the area.
Once you are down there, you will need to fight off some spiders. Watch out for their teleportation. Keep in mind you can use fire to burn the webs and cause them to fall. However, touching the webs will alert them of your presence. Once you find the Queen Matriarch, you will be able to see the Dark Amethyst you need just below on the ground near the chasm. Try to kill the eggs around the arena before she makes them hatch, as they each spawn a spiderling that can also teleport.
Once you defeat her and grab the gem, you can now open the book and peer inside. Using the book will allow you to learn the Speak With Dead spell, allowing you to converse with corpses you find or create and probe them for more information assuming they want to talk. It also grants you the Forbidden Knowledge trait, which gives you a +1 bonus to Wisdom Saves.
However, if you do not want its dark magic, there is also a path to destroy it. The book is resistant to most types of damage, but it can be destroyed with Radiant damage (EX: Shadowheart's Guiding Bolt, or Sacred Flame). Simply drop the book on the ground and attack it with some Radiant damage, and it will summon three Evil Shadows to fight. They have high resistance to most physical things so try using spells for the majority of the fight to make it easier. Slay them for no other reward than some experience and closure knowing that you did a good thing.