The Necrotic Laboratory puzzle is one of the most difficult puzzles Baldur’s Gate 3 will occasionally throw your way to solve. This puzzle tests your wit and your ingenuity. It will be downright frustrating if you do not approach it with an open and observant mind.
You will encounter The Necrotic Laboratory Puzzle during Act 2, after your first battle with Ketheric Thorm. This puzzle involves linking several color-coded nods, which, when you complete it, gives you access to unique rewards.
The Necrotic Laboratory can be found underneath the Moonrise Tower. The Moonrise Towers are located in the Shadow-Cursed Land area just South of the Grand Mausoleum. You will get to the Shadow-Cursed Lands after you pass through the Underdark. The trek from the Mausoleum to the towers is a long one.
Refer to the map picture above to find the exact location. You must first initiate the Ketheric Thorm quest to get to the Lab. The first phase of this quest takes place on the roof of the towers, after which he escapes into the tunnels. Follow him there, and simply following the path will get you to the Necrotic Puzzle.
How to solve Baldur’s Gate 3 Necrotic Laboratory Puzzle
The puzzle is quite difficult and involves linking together different colored nodes in order to access the next area. There are four brains, each colored differently to represent a specific feature. The purple brain represents reason, the green and yellow brains represent memory and reason, and the blue brain represents speech.
Purple Brain
You must link the nodes in the correct pathway to solve the Necrotic Laboratory puzzle. For the Purple Brain, link all the nodes at the top of the 3D structure. Manipulate the model until you can see the top nodes clearly, as it can be difficult to make it out without scrutinizing it. Follow the picture below to complete the first portion of this puzzle.
Green Brain
For the Green Brain, first, connect the initial node to the bottom node, then connect it to the one right in front of it (towards the north). Next, go further north and connect it to the highest point right in front of the previous node, then finally connect the nodes to the two nodes on the left. The picture below will give you a better understanding.
Yellow Brain
For the Yellow Brain, connect to the node right in front of the brain, then to the one directly to the left, and continue straight onto the next. Lastly, connect to the immediate node on the left and then to the final one on its immediate left. The picture below will give you a better understanding.
Blue Brain
Finally, for the Blue Brain, first, connect to the free node towards the top of the structure, then connect to the free node directly in front of it (the one facing south), and finally connect to the last two nodes on its immediate right. Use the picture below as a reference point.
Necrotic Laboratory Puzzle Rewards
Completing the Necrotic Puzzle in BG3 opens the door right before you. You can then continue with the Ketheric Thorm quest. Within the room, you also receive three rewards. These rewards include the likes of the Blade of Oppressed Souls, the Braindrain Gloves, and the Circlet of Mental Anguish.
| Reward | Attributes |
| Blade of Oppressed Souls (+1 Longsword) | 1D10 (Slash Damage), 1D4 (Psychic Damage) |
| Braindrain Gloves | Causes fatigue in enemies for two rounds if you inflict psychic damage |
| Circlet of Mental Anguish | Recovers HP when the enemy fails a saving throw against your spells. |
