This page of the Baldurs Gate 3 guide describes how to safely take the Necromancer's Book from the laboratory in the basement. It is protected by powerful traps that can quickly kill a hero trying to steal the book.
As a reminder, the Necromancer's Book is found in the Necromancer's basement. The building you need to explore is located in the southeast part of Blighted Village. You need to locate the hatch leading to the basement and then give the correct answers while talking to the mirror.
You'll get to the Necromancer's lab. The Necromancy of Thay is stored in the eastern part and the door to the room with this artifact is required to be opened, using the thief's tools.
Don't try to take the book right away. It lies on a pressure plate, the release of which will trigger the traps:
- The door will close behind the hero.
- Fire traps are triggered, inflicting severe fire damage.
In order to safely remove the Necromancer's Book, you must place some other object on the pressure plate. For example, you can find another book in the lab and move it towards the artifact room (hold down the Left Mouse Button and move it to another place).
Place another book (or another object of similar size) on a pressure plate next to the Necromancer's book. You can safely pick up The Necromancy of Thay and leave the press-plate room with it.