Confront the Elder Brain

The Elder Brain is the ultimate opponent, and the one way to escape the tadpoles.

Confront the Elder Brain is a quest in Act Three of Baldur's Gate 3.

Objectives

Follow the Chosen to Baldur's Gate.

• We can thwart the Chosen of the Dead Three by taking control of the elder brain - but will we use that control to liberate or to conquer? ** * Whatever the answer, it lies in Baldur's Gate.

Obtain the three Netherstones.

• We have finally arrived in Baldur's Gate. To face the elder brain, we must obtain the Netherstones from the three Chosen. We already have Ketheric's Netherstone.
• We have obtained Orin's Netherstone.
• We have obtained Gortash's Netherstone.

Meet Gortash at the Morphic Pool.

• We made a deal with Gortash. He is waiting for us under the city at the Morphic Pool, where the elder brain feeds.

Face the elder brain.

• The elder brain killed Gortash and we took his Netherstone.
• With all three Netherstones in our possession, it is time to go to the Morphic Pool and face the elder brain. We should head to the sewers.
• The time has come to face the elder brain.

Talk to the Emperor.

• We tried to dominate the elder brain, but it has become too powerful to submit to orders. The Emperor might know what went wrong.

Get a mind flayer on your side.

• We drove the Emperor away - it has joined sides with what we now know to be a Netherbrain.
• We struck a deal with Raphael. He will give us the Orphic Hammer to free Orpheus - our last chance to defeat the Netherbrain - and, in exchange, we will give him the Crown of Karsus when we triumph.
• We have freed Orpheus from the globe of domination.
• We learned that only a mind flayer will be capable of wielding the stones to dominate what we now know to be a Netherbrain.

Face the Netherbrain again.

• We have become illithid. We should now be able to dominate the Netherbrain.
• Orpheus has become a mind flayer. We should now be able to dominate the Netherbrain.
• Karlach has become a mind flayer. We should now be able to dominate the Netherbrain.
• We gave the Netherstones to the Emperor. We should now be able to dominate the Netherbrain.
• The Emperor gave us a Supreme Tadpole, which will transform whomever consumes it into a mind flayer. If we are to defeat the Netherbrain, we must have a mind flayer on our side.

Get to the Netherbrain.

• The Netherbrain has made its way to the High Hall. We are going to have to fight or sneak our way through to reach it.
• We reached the brain stem. It's time to climb up and end this once and for all.
• We made the ultimate sacrifice and became illithid. We should now be able to control the Crown once we reach the Netherbrain.
• Karlach made the ultimate sacrifice and became a mind flayer. We should now be able to control the Crown once we reach the Netherbrain.
• The Netherbrain has made its way to the High Hall. We are going to have to fight or sneak our way through to reach it.

Reach the Crown of Karsus.

• The Crown sits atop the Netherbrain, sending out an intense, pulsing aura. It's now or never: we must take control of the Crown of Karsus.
• Karlach made the ultimate sacrifice and became a mind flayer. We need to help her so she can cast Karsus' Compulsion on the Crown.
• We made the ultimate sacrifice and became illithid. We need to cast Karsus' Compulsion on the Crown.

Enter the portal to the Netherbrain's psyche.

• We successfully cast Karsus' Compulsion and can now enter what looks to be the Netherbrain's psyche manifested as a plane of existence.

Bring the Netherbrain to heel.

• We're in the mind of the Netherbrain, where its unbreakable will is manifested in physical form. If we can break it, we can bring the Netherbrain to heel.

Quest Complete

• We conquered our parasites, defeated the Netherbrain, and took control of our own destinies. We did it. We won. We won!

Walkthrough

Confronting the Elder Brain

The reveal

Confront the Elder Brain is acquired at the end of Act Two, after the Chosen Three are revealed to be controlling the Elder Brain as part of their plot to take over Baldur's Gate. However, the quest cannot be meaningfully progressed until Get Gortash's Netherstone and Get Orin's Netherstone have successfully been completed. Orin must be defeated and Gortash must either be defeated or his bargain accepted as part of Consider Gortash's Bargain. Defeating both Orin and Gortash causes a vision of the Elder Brain in the Morphic Pool beneath the city. If Gortash is allied with, then he reveals the Elder Brain's location and tells the party to use the boat under the city to meet him there.

The Morphic Pool Dock is north of the Temple of Bhaal waypoint. Approaching the dock before obtaining all three Netherstones results in a swarm of cranium rats attacking.

Note that going on the boat to the Morphic Pool is the start of the endgame. After this, it is not possible to long rest or visit camp. Plan accordingly and choose the desired companions for the final battles.

The Morphic Pool

Map of the Morphic Pool

Arriving at the Morphic Pool, the party must make several Constitution checks to not be mindbroken by the Elder Brain. It speaks to the party, demanding obedience. As the party moves further north, a Perception check reveals an ambush oncoming which can be avoided by sneaking through the whole area. The party is attacked by several Intellect Devourers and Intellect Glutton. The Emperor remarks that something is corrupting the creatures.

Once the Morphic Pool's waters are reached, the party takes control of the Netherstones to confront the Elder Brain, which has become a Netherbrain, in a number of difficult checks:

• [STRENGTH] Muster the full might of your physical form - throw it into breaking through the brain's defences. (DC 20)
• [INTELLIGENCE] Your mind is yours to command - block out all possibility of failure and compel the brain to submit. (DC 20)
• [CONSTITUTION] You have survived this far - trust yourself. Dominate the brain. (DC 20)

The brain continues to taunt the party. She says the Chosen Three controlled her only for as long as she allowed them to.

• [DEXTERITY] The Crown is an unmissable target - set it in your sights, and trust that you will strike true. (DC 25)
• [WISDOM] A first attempt is just that - iteration is key. Aim for the Crown and try again. (DC 25)
• [CHARISMA] Nothing is immune to influence - determine to master the brain. (DC 25)
• Bow before the glory of the Netherbrain. Submit to domination.

The Netherbrain tells the party she was the one who informed the Chosen of the Astral Prism and planted fear of what Orpheus could do to their plan. She was the one who let the Emperor slip its leash so that it could retrieve the prism and loosen the Netherstones from the Chosen Ones' grasps.

• [STRENGTH] You are strong. You are mighty. You will dominate the brain. (DC 30)
• [CONSTITUTION] Your resilience will not be shaken - cast the spell again. (DC 30)
• [INTELLIGENCE] It may not be easy, but it was always supposed to be possible - do it again. (DC 30)
• Bow before the glory of the Netherbrain. Submit to domination.

One final, near impossible check remains. The result of the check is inconsequential, as the Netherbrain is too powerful.

• [STRENGTH] DOMINATE THE BRAIN (DC 99)
• [DEXTERITY] DOMINATE THE BRAIN (DC 99)
• [INTELLIGENCE] DOMINATE THE BRAIN (DC 99)
• [WISDOM] DOMINATE THE BRAIN (DC 99)
• [CHARISMA] DOMINATE THE BRAIN (DC 99)
• Give up. Allow the brain to dominate you.

Regardless of what the party does, the brain is simply too powerful, and the Emperor steps in to save them by bringing everyone inside the Astral Prism.

the Emperor states that only an illithid can hope to take down the Netherbrain in its current form and that the illithid must consume the power of Prince Orpheus in order to succeed. As an illithid, the Emperor says he can do this, and asks the Netherstones be relinquished to him.

If the party rejects the Emperor's proposition, he states that he has no other choice but to reassimilate with the Netherbrain, and leaves the party in the Astral Realm. This can be done by selecting "I don't believe a word you just said" followed by "I will never trust you", or by asserting the intent to free Orpheus if the party possesses the Orphic Hammer. Afterwards, if the party has the Orphic Hammer, they can equip it and attack the crystals binding Orpheus.

There is also the possibility of the party not retrieving the Orphic Hammer and spurning the Emperor. In this case, Raphael appears within the Astral Prism. He has front row seats to the final hour, and now he's come with the sole salvation of Faerun. There are no more deals: only master and vassal. Sign a contract for the Orphic Hammer in exchange for the Crown of Karsus, or the world ends. Failing to uphold the bargain means the party's souls are forfeit. Refusing to sign turns the party into mind flayers who assimilate into the Netherbrain, causing a game over. The party is forced to Fulfill the Deal.

Once Orpheus is freed, he confronts the party on their choices, saying the party should have let his honor guard kill them so they could have avoided this whole situation. He also confronts the party if they stole the Githyanki egg in Steal a Githyanki Egg. However, he agrees to stand down and works with the party. He states that the Emperor was correct and an illithid is necessary to take down the Netherbrain. Either a party member can make the sacrifice, or Orpheus will if everyone refuses.

Otherwise, the party can choose to work with the Emperor. The Emperor can be given the Netherstones and he assimilates Orpheus by devouring his brain. Another possibility is for Karlach to volunteer to become an illithid, as she is dying from her infernal engine anyways. The player character can also volunteer to become illithid. Whoever becomes illithid can wield the stones.

Regardless of who is allied with, Orpheus/the Emperor joins the party as a temporary companion and opens up a portal to the High Hall. The final battle to defeat the brain has begun.

The High Hall

Map of the High Hall

Map of the Upper City Sewers

The party returns to Baldur's Gate to find it in shambles. The entire city is a battle between the Nautiloids and an army of Red Dragons. Moving forward, the party finds a building where all of their allies are gathered, along with a Flaming Fist named Beorn Wunterbrood. The individuals that appear are based on who was successfully recruited as part of Gather Your Allies. These allies grant a new action - Call Forth Allies - that can summon various allies to the field or utilize powerful AoE attacks.

Before entering the courtyard, the party can potentially encounter a few mindflayers if they move eastward. There is also a restoration pod right near the gate to the courtyard. (not if played on tactician) Entering the courtyard leads to an all-out assault of Absolutist cultists, goblins, an Ogre, a Spectator, and several Mind Flayers. Note, it is possible to bypass this battle by avoiding entering through the main entrance, and approaching the High Hall from the northern or southern routes with stealth and invisibility.

Additionally there is a hidden route through Upper City Sewers which also lead to High Hall proper. This route features few goblins, a mindflayer, Absolute cultist, necromites and a Death Knight named Stalker Svignee.

Once the courtyard battle is completed, the party enters the High Hall proper. A Nautiloid attacks, and there is a turn limit to get deeper into the Hall. The party faces several Banite cultists and needs to push a statue (with a Strength check) to climb up to the upper floor. Moving past the cultists is the brain stem of the Netherbrain. Approaching the stem causes an automatic cutscene and ends the turn limit. From there, the party can use a restoration pod and then climb the stem, to get to the top of the Netherbrain. If Gale is in the party, it's noted that Gale could use the bomb to end the battle right away. Gale notices the hesitation before climbing the stem and asks what the plan is, and he can either be told the proposal or simply told it was nothing.

Atop the Netherbrain

If Orpheus was sided with rather than the Emperor, the Emperor appears on top of the Netherbrain to stop the party. The Emperor conjures up several Dream Visitors to fight alongside him, stating he knows the party's every weakness. He is joined by several Mind Flayer Arcanists and an enthralled Red Dragon. If the Emperor is sided with, the Netherbrain itself sends several powerful thralls to join the Red Dragon and Arcanists. The thralls are mirrors of parties members and gain same ability scores and classes.

The Netherbrain has two paths to the east and west which allow the party to traverse the brain without stepping on the brain matter. If the party traverses the brain matter, tentacles pop up to attack the party. There are a limited number of turns until a Nautiloid ship arrives. The illithid party member that holds the Netherstones needs to reach the Crown of Karsus and perform Karsus' Compulsion for several turns.

Successfully casting Karsus' Compulsion opens up a portal to the Netherbrain, where a physical manifestation of the brain can be attacked. Killing the brain before the turn limit allows the brain to be defeated, once and for all.

After the Netherbrain has been defeated, the choice must be made to either Control the Elder Brain or Destroy the Elder Brain. Regardless of the choice, this is the end of the game.

Allies in the Final Fight

Ally Powers

Ally	Benefit
Weavewalker	One must remove all obstacles to follow one's destiny - Arabella's favour grants affected entities benefits of Freedom of Movement.
Fetcher's Favour	Equipped with Mol's tricks of the trade, affected entities can cast Rays of Fire, reduce all Fire damage by 5 and gain an additional 1d4 to Charisma Checks and Saving Throws.
Volo's Guide to Monsters	With steadfast application of knowledge from Volo's preeminent work, affected entities gain +2 to Attack Rolls, Saving Throws, and Ability Checks.
Spirit of the Land	The reunited soul of Thaniel provides a +1 to all Ability Scores and an additional 2m movement speed to all affected entities.
Rallied	Add 30 HP
Orphic Favour	While within 18m of Prince Orpheus, the affected entity has Resistance to Psychic damage and a +3 bonus to Intelligence, Wisdom, and Charisma Saving Throws.
An Apple a Day	Summon Zlorb - a shapeshifting monstrosity that can adopt the aspect of several monsters and beasts.
Battle-Ready Owlbear	Summon your owlbear cub - all grown up and ready to rage - in full armour.
Hellstalker Yurgir	Summon Yurgir the orthon - a deadly combatant at range or in melee who can become Invisible immediately after attacking.
Sword of the Silverlight	Summon Dame Aylin, Selune's shining paladin, to join your side in battle.
Balm of the Moonmaiden	Call upon Isobel to offer a furtive prayer to Selune, healing up to 6 nearby allies.
The Watch	Summon some of the City Watch's great weapon fighters to protect their home.
Hellrider Platoon	Summon Zevlor's Hellriders to Smite foes and support frontline allies.
Guildmaster Keene's Fixers	Summon two elite assassin mercenaries from the Guild's ranks.
Zhentarim
Silver Harp Squadron	Summon elite Harper archers to provide ranged support from your back ranks.
Gur Huntwards	Summon Gur monster hunters to hinder enemies while slipping in and out of the frontlines.
Vampire Lord Astarion
Ironhand Grenadiers	Summon the Ironhand Gnomes to damage and debilitate with thrown grenades.
Florrick's Cohort	Summon Florrick's personal guard - highly defensive warriors who can hold their own in melee.
Rolan's Firestorm	Damage: 20-120. Call upon Rolan, freed from the limitations of Lorroakan, to unleash a fiery barrage from the heights of Ramazith's Tower.
Lorroakan
Kith'raki Inferno	Damage: 12-72. Command the red dragon of Supreme Kith'rak Voss to breathe a wall of fire onto the battlefield.
Mizora, Agent of Avernus	Summon Wyll's pactmistress to rain down powerful infernal sorcery and possibly Disintegrate your foes.
Viconia
Dark Justiciar Shadowheart
Bhaal's Slayer
Hag

Notes

• As of Patch 1, there is a bug where Karlach's ending causes an epilogue scene with a love interest not to occur. If Karlach goes to Avernus instead of dying, it's possible that this scene overwrites the romantic scene.
• Despite being a possible ally in Gather Your Allies, the Gondians do not appear to have a summon/ability.