Editing The Netherbrain/combat

{{PageSeo
| title = Fighting The Netherbrain
| description = The Netherbrain is the final boss of Baldur's Gate 3. This page deals with its combat encounter.
| image = Netherbrain_Illusion.webp
}}
{{Infobox statistics
| image = Netherbrain Model.png
| str = 14
| dex = 10
| con = 22
| int = 28
| wis = 21
| cha = 24
| con_save_proficiency = y
| int_save_proficiency = y
| wis_save_proficiency = y
| cha_save_proficiency = y
| level = 20
| name = The Unbreakable Will of the Netherbrain
| size = Huge
| type = Aberration
| race = Elder Brain
| armour_class = 15
| hit_points_tactician = 450
| hit_points = 300
| movement_speed_meters = 0
| movement_speed_feet = 0
| weight_kg = 10000
| weight_lb = 20000
| initiative = -15
| condition1_name = Chains of Karsus
| condition1_description = Will break free of its domination within 5 turns
| condition2_name = Against All Odds
| condition2_description = Begins with 20% of its HP missing, depending on an earlier ability check
| condition3_mode = Honour
| feature1_name = Psionic Retribution
| feature1_description = Use a reaction to release a brainquake
}}
{{CombatTab}}
This page focuses on [[The Netherbrain|The Netherbrain's]] behavior during turn-based combat gameplay.

== Attacks and abilities ==
{{Feature box|name=Retributive Brainquake|image name=Generic Psychic.webp
|* As a reaction to taking damage, deal {{DamageText|10d6|Psychic}} damage to all enemies within 30m and {{cond|Mindbroken|Mindbreak}} them.
* {{Saving Throw|INT}} to halve damage.
}}

{{Feature box|name=Orb of Negation|image name=Generic Explosion.webp
|* Summon several floating orbs which deal {{DamageText|20~200|Force}} damage to everything within range at the end of the next round.
}}

=== Honour Mode ===
{{Feature box|name=Aegis of the Absolute|image name=Aegis of the Absolute.webp
|* The Netherbrain can make itself [[Immune]] to all types of damage it took in a round of combat until the start of its next turn.
}}


== Conditions ==
* {{cond|Chains of Karsus}} - After using [[Karsus' Compulsion]] on the Netherbrain
* {{cond|Against All Odds}} - If a natural 20 was rolled on the final check to dominate the Netherbrain at the [[Morphic Pool]] it will have this condition, which reduces its HP by 20%.

== Allies ==
* [[Dominated Red Dragon]]
* 4x [[Illithid Arcanist]]
* 16x [[Tentacle]] (hidden under the brain's surface until approached)
* [[Nautiloid (Creature)]] (appears after a 4 turn countdown and begins summoning [[Mind Flayer]]s and [[Intellect Devourer]]s)

=== Conditional Allies ===
* [[The Emperor]] (if the player chose to free Orpheus)
* 4x [[Dream Guardian]] (if the player chose to free Orpheus)
* 4x [[Countermeasure]] (if the player chose to trust the Emperor)

== Encounter ==
===Atop the brain===
* The objective of the first phase is to make it to the [[Crown of Karsus]] and channel [[Karsus' Compulsion]] on it to enter the Netherbrain's psyche and defeat it for good.
* Stepping directly on the brain's surface will summon up to 16 hidden [[tentacle]]s, so it may be easier to approach from the two platforms on either side. 
* Once the party has reached the Crown of Karsus, the party member with [[Karsus' Compulsion]] must channel it in order to enter the final stage of the fight. The channelling lasts for 2 turns (the turn it was started and the following turn) and on the 3rd turn a portal will open to the Netherbrain's psyche (or '''The Unbreakable Will of the Netherbrain''').
* Only party members and either [[Orpheus]] or the [[Emperor]] can enter this portal, so once it has been opened there is no reason to continue fighting other enemies.
* Once all party members and Orpheus/the Emperor have entered the portal, the battle outside on the surface of the brain will end and the remaining turn order will just consist of the party and the Netherbrain.

=== Inside the crown===
* It is strongly recommended to have the entire party near the portal before completing [[Karsus' Compulsion]]. Once the portal is opened, the final fight against the Netherbrain begins immediately and it must be defeated before it destroys all the platforms inside.
* While allies summoned through [[Gather Your Allies (Class Action)]] cannot enter the portal, they can be summoned onto the platforms inside.
* The Netherbrain will use {{SAI|Orb of Negation}} to summon several orbs which deal damage at the end of the next round and destroy the platforms beneath them, so it is important to move characters off of any marked platforms. These Orbs will disappear upon the brain's death.
* The Netherbrain must be killed quickly since every platform will be destroyed in only a couple of turns.

==Tactics==
===Atop the brain===
* {{SAI|Dimension Door}}, {{SAI|Arcane Gate}}, and {{SAI|Misty Step}} are all useful spells/scrolls for moving from the entrance [[Confront the Elder Brain#Atop the Netherbrain|Atop the Netherbrain]] to the Crown of Karsus. Otherwise, if intending to sprint past the tentacles hidden under the brain's surface, it is helpful to use a character who can avoid [[Opportunity Attack]]s, such as one with the [[Mobile]] feat.
* {{SAI|Globe of Invulnerability}} and {{SAI|Sanctuary}} are useful for protecting the caster of [[Karsus' Compulsion]]. However, the nearby [[Illithid Arcanist]]s will still be able to {{cond|Stunned|stun}} creatures affected by these spells, which disrupts the spell prematurely.
* The four [[Illithid Arcanist]]s are very dangerous enemies in this section of the fight. They can spam a more powerful version of {{SAI|Magic Missile}}, use {{SAI|Counterspell}}, stun your party via {{SAI|Tentacle Whip}} and {{SAI|Mind Blast}}, and even gain control of allies with {{SAI|Mind Flayer Domination}}. They are also immune to being pushed over the edge with moves like [[Telekinesis]], as they will just reappear atop the Netherbrain. Fortunately they have a rather low number of hit points, making them vulnerable to allies with high maneuverability and damage. 
* While choosing to ally with the Emperor over Orpheus results in less total enemies during this fight, the [[Countermeasure]]s are far more dangerous than the [[Dream Guardian]]s. Some of them have powerful disruptive abilities such as {{SAI|Counterspell}}, {{SAI|Psionic Dominance}}, {{SAI|Goading Attack (Melee)}}, {{SAI|Slow}}, {{SAI|Black Hole}}, and {{SAI|Confusion}} which can severely hinder an unprepared party. Others have significantly more hit points (see [[Rage Queller]]) or deal far more damage through {{SAI|Improved Extra Attack}} and {{SAI|Action Surge}} (See [[Breaker of War]]).

=== Inside the crown===
* Casting {{SAI|Feather Fall}} before entering the portal can allow melee range party members with low movement speed to immediately jump down to the brain and begin attacking it.
* The first attack each round against the Brain will cause it to use {{SAI|Retributive Brainquake}}, which will damage and possibly {{cond|Slowed|Slow}} everything in range. The player can potentially avoid this the first time by triggering it with the first party member to enter the portal, and then having the rest of the team enter afterword.
* {{SAI|Dimension Door}} and {{SAI|Misty Step}} can help party members reach safe platforms if the ones they are on have been designated for destruction.
* On ''Honour Mode'', the Netherbrain will augment itself with {{SAI|Aegis of the Absolute}}, making it immune to damage types that were used agains it on the previous turn. It is important to plan ahead exactly which attacks will be used against it so that the party doesn't miss entire turns where the brain is immune to all their attacks. 

==Achievements==
{{Achievement|Hero of the Forgotten Realms}}
{{Achievement|Absolute Power Corrupts}}
{{Achievement|Sins of the Father}}

== Bugs ==
* Thrown weapons that return to the user, such as {{RarityItem|Nyrulna}} or {{RarityItem|Returning Pike}}, may occasionally fall into the chasm below the Netherbrain and disappear forever after being thrown at it. Throwing builds should bring back-up weapons just in case.
[[Category:Bugs]]

[[Category:Combat guides]]