BG3 screenshot of player character standing in front of Elder Brain

Baldur’s Gate 3: How to Find and Confront the Elder Brain (BG3)

Bring your favorite brain some diamonds

You’ve wrested away the stone from the God of Murder’s chosen, proving that you are the true letter of blood, and now all that stands in your way is a giant brain. We’ll tell you how to find and confront the Elder Brain in Baldur’s Gate 3.

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Baldur’s Gate 3: Elder Brain Location in Lower City (BG3)

The quest is titled Confront the Elder Brain. It is in Act 3 and is given in the High Hall. You’ll need to have found all three Nether stones ahead of time. The Gather Your Allies quest is fairly important to this.

Fortunately, if you’ve spent much time crawling around the city sewers, getting to the Elder Brain isn’t that hard. In fact, you only need to go North from the Temple Bhaal Waypoint

Yes, when you freed your companion from Orin’s altar (or not, this is a judgement-free zone), you were only a few minutes from the Elder Brain. You just need to snake your way through the abandoned houses until you find yourself at the shore of a dark, black lake. 

BG3 screenshot of the Lower City sewers map, with a red square around the Elder Brain location in the Undercity Ruins.
Screenshots by Prima Games

If you don’t have all the Netherstones, the Emperor will warn you away from this area and reveal that this is where the Elder Brain was kept all along. Here, in the water, just below the city. If only to give the illusion that everything was under control when it most decidedly wasn’t. 

Continue following the lake’s shore until you find a bunch of mice with glowy-purple eyes. These mice are linked in a hivemind and you don’t even need Speak to Animal to talk to them. Go past them, down the pier, and you’ll find both a waypoint and a skiff.

Note once you set sail on the skiff, you’ll be ending your time in the Lower City. You’ll go to a brand new area, from which the Lower City will be inaccessible. If you haven’t finished up your side quests in Lower City, now’s a good time.

Tip:

In particular, you’ll want to make sure you’ve done all you can with the Gather Your Allies quest. This quest will come in handy during your march up to the Elder Brain, as it gives you access to several powerful allies and their skills.

Confront the Elder Brain Quest Objectives

You’ll begin the Confront the Elder Brain Quest way back at the end of BG3’s Act 2, once you actually find out about the Elder Brain’s existence and the Chosen Three. And now that you know about the source of your problems, Act 3 will have you looking for a way to confront the real threat to Baldur’s Gate. Here’s all the objectives for the Confront the Elder Brain quest and how to approach them.

Follow the Chosen to Baldur’s Gate

So you’ve taken down the first of the Chosen Three, and the other two have run off to Baldur’s Gate to prepare for an incoming invasion and world domination. Before you do anything, you’ll first need to follow them and reach the city.

The path to Baldur’s Gate is in the eastern-most part of the Shadowlands map, ahead of a waypoint aptly named “Road to Baldur’s Gate.” It’s right beside The Waning Moon Tavern. Follow through here, and you’ll enter Rivington: a short gateway that leads to the entrance of the city. At the far end will be your entrance to the Lower City, but you’ll need to find a way around the raised bridge blocking Wyrm’s Crossing.

Obtain the Three Netherstones

Now that you’re in the city proper, you won’t be able to confront the Elder Brain until you gather the three Netherstones controlling the Elder Brain’s Crown of Karsus. You already got one after defeating Thorm in Act 2. The other two you’ll have to pry away from Orin the Red, a maniacal sociopath in service of a murder god, and Gortash, Baldur’s Gate’s newly ordained lord raised to power by a devil.

Gortash you’ll meet right away at Wyrm’s Crossing, but he’ll be heavily guarded and getting rid of him immediately won’t necessarily be the smartest thing to do. Check out our full guide on how to reach Gortash and beat him for an in-depth walkthrough on how to approach Baldur’s Gate’s new lord.

You’ll eventually confront Orin the Red at Temple Bhaal in the city’s sewers. But she’ll be difficult to reach, and you’ll have to jump through some hoops to get there. You can check out our full guide on how to beat Orin for an in-depth walkthrough on how to find and deal with the prodigal murder fiend.

SPOILER WARNING:

At this point, we’ll start to address what happens after the point of no return. We’ll try to be vague enough to refrain from any large spoilers while still concise enough to guide you through the next steps, but there will be mention of general story beats as you move forward. Make sure you’re prepared and ready to end the game before you proceed any further.

BG3 screenshot of the Elder Brain
Screenshot by Prima Games

Face the Elder Brain

Tip:

If you want to follow Lae’zel’s and Gale’s questlines to completion, you’ll want to make sure you have them in your party before heading over to the Elder Brain’s location. You can also take Karlach with you to have some influence on her fate as well, depending on the choices you make going forward.

Once you have the three Netherstones in hand and you’re ready to go after the Elder Brain, you’ll want to take the skiff in the north sewers. After you reach land, follow the linear rocky path forward. You’ll have a brief battle with a group of Intellect Devourers, but they shouldn’t pose much of a problem. Once they’re all dealt with, you can move forward, and at the end of the pathway, you’ll finally stare down your nemesis face to face. Here you’ll have a chance to pass three various dice checks that get progressively harder. But don’t worry too much if you don’t pass them. Things will end the same way regardless.

Talk to the Emperor and Get a Mind Flayer on Your Side

The Emperor will come to your rescue and pull you into the Astral Prism. This is where you’ll make some of the most important decisions in the game. If you’re following Lae’zel’s quest and managed to nab the Orphic Hammer before this point, this will be your chance to free Orpheus. Otherwise, you’ll need to decide how you want to approach the final battle. Once you talk it out with the Emperor and have made your decision, proceed through the portal to the High Hall.

BG3 screenshot of red dragons attacking a nautiloid
Screenshot by Prima Games

Face the Netherbrain Again and Get to the Netherbrain

When you get to the High Hall, the pathway will yet again be fairly linear. Follow it, and you’ll eventually come across an Illithid restoration pod. Use it if you need to, and then prepare yourself for a long battle in the High Hall Courtyard. Technically you can sneak your way through if you have the means to make yourself invisible or are quite skilled in stealth, but more likely, you’ll have to fight your way through an army of goblins, zealots, mind flayers, winged horrors, and intellect devourers.

To help you in this fight, you can call forth allies using the button prompt at the bottom of the screen. The allies available to you depend on who you have helped throughout the game, and who you recruited for the Gather Your Allies quest. Many allies can only be used once, and you’ll have one more upcoming battle to fight through, so consider their use carefully.

Tip:

With the summon button prompt, you are able to summon as many allies as you want. In total, there are 30 possible recruits you can acquire throughout the game. Make sure you don’t summon too many at once, as once they die, they’re gone forever. You’ll want to space them out to ensure you have plenty of help during the fight.

Your ultimate goal is straight ahead through the large double doors and up the many stairs to the Brain Stem. There are many enemies to cleave your way through, but the actual path forward is pretty short and simple. Once you start climbing the stairs past the large double doors, you’ll have to dodge fire from an Illithid Nautiloid. Its damage area will be outlined as an orange circle on the floor. Avoid these circles as much as possible.

When you reach the wooden double doors at the top of the stairs, the fight will end, and you can use a restoration pod to heal yourself up before climbing up the Brain Stem. Prepare yourself as you’re about to enter the final battle.

Tip:

If you have Gale in your party, you can choose to have him climb the Brain Stem alone and end the game here. This decision will skip the final battle and play out the rest of the game through a series of cutscenes. Otherwise, choose to go with him to enter the final battle.

BG3 screenshot of the dominated red dragon about to take flight in front of the Netherbrain
Screenshot by Prima Games

Reach the Crown of Karsus and Enter the Portal to the Netherbrain’s Psyche

Now that you’ve made your way atop the Netherbrain, you’ll need to have your mind flayer make their way up to the Crown of Karsus and cast Karsus’ Compulsion to dominate the Netherbrain. The rest of your party will have to contend with a group of mind flayers, some grabby tentacles, and a dominated red dragon. After four turns, a Nautiloid will also appear and start firing upon the brain. Depending on your choices, you may have a few other enemies against you as well.

You won’t actually need to defeat every enemy atop the Netherbrain, you’ll just need to endure. The biggest threat on the battlefield are the mind flayers. They’ll each cast a high level Magic Missile every turn, inflicting dozens of damage to their targets. Taking them out should be a top priority. The red dragon is also a high threat, but it can easily be taken out by a few strong melee attacks, and it doesn’t actually inflict as much damage as the mind flayers can.

Once Karsus’ Compulsion is complete, a portal will open up that will lead to the Netherbrain’s psyche. Your mind flayer that casted the spell will automatically enter the portal, but you’ll also want to get your other party members in there as quickly as you can. This will take them away from the hoard of enemies, and you’ll then be able to focus your attacks on the Netherbrain.

BG3 screenshot of the unbreakable will of the Netherbrain in the mind of the Netherbrain
Screenshot by Prima Games

Bring the Netherbrain to Heel

Inside the Netherbrain’s psyche, you’ll have five turns to defeat it before it breaks out of its chains and turns everyone into a thrall, causing a game over. Luckily, this isn’t too tough.

Tip:

If you haven’t yet used all of your available allies, we recommend using them here. This will be your last chance to use them and they can help speed things up in your strict time limit. Dame Aylin in particular can make very quick work of the Netherbrain here.

The Netherbrain has 210 HP and Psionic Retribution, which will release brain quakes, inflicting 10-60 damage as a reaction attack to all party members within 30m. Its only other move is to send out an Orb of Negation, which will target an area and destroy any platforms and any party members in that area at the end of the orb’s turn. But this is easily avoidable and the brain is soft and squishy. It will go down after just a few quick hits.

Once you knock the brain down to 0 HP, you’ll have one final decision to make. And then congratulations! You’ve beaten the game. Now sit back and enjoy the ending to your long, long journey.

The end to BG3’s Confront the Elder Brain quest is a long process, and you’ve probably struggled with some decisions along the way. If you’re wondering how things might’ve turned out differently, find out what happens if you do or don’t free Orpheus in BG3


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Daphne Fama
A Staff Writer at Prima Games since 2022, Daphne Fama spends an inordinate amount playing games of all stripes but has a soft spot for horror, FPS, and RPGs. When she’s not gaming, she’s an author and member of the Horror Writers Association with a debut novel coming out in 2025. In a previous life, she was an attorney but found she preferred fiction to contracts and forms
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Seth Lowe
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