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The Netherbrain/Combat

From bg3.wiki

This page focuses on The Netherbrain's behavior during turn-based combat gameplay.

Spells and abilities

Retributive Brainquake Retributive Brainquake ()
D6 Psychic.png 10d6 (10~60) Damage TypesPsychic

Upon first time that you take damage in a turn, emit a wave of psionic force that Mindbreaks Mindbreaks nearby enemies.

INT Save
 Range: 30 m / 90 ft
Orb of Negation Orb of Negation ()
The Grand Design cannot be disrupted - manifest an orb of Netherese arcana that explodes on its turn, obliterating everything within range.
 Range: 30 m /  ft

Honour Mode

Aegis of the Absolute Aegis of the Absolute
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.
 Range: 18 m / 60 ft
Recharge: Per turn


Conditions

Enemy allies

Conditional enemy allies

Encounter

Atop the brain

  • Dimension Door Dimension Door, Arcane Gate Arcane Gate and Misty Step Misty Step are all useful spells/scrolls for moving from the entrance Atop the Netherbrain to the Crown of Karsus.
  • Stepping directly on the brain's surface will summon up to 16 hidden tentacles, so it may be easier to approach from the two platforms on either side. Otherwise, if intending to sprint across, it is helpful to use a character who can avoid Opportunity Attacks, such as one with the Mobile feat.
  • Globe of Invulnerability Globe of Invulnerability and Sanctuary Sanctuary are useful for protecting the caster of Karsus' Compulsion. However, the nearby Illithid Arcanists will still be able to stun stun creatures affected by these spells, which disrupts the spell prematurely.
  • The four Illithid Arcanists are very dangerous enemies in this section of the fight. They can spam a more powerful version of Magic Missile Magic Missile, use Counterspell Counterspell, stun your party via Tentacle Whip Tentacle Whip and Mind Blast Mind Blast, and even gain control of allies with Mind Flayer Domination 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 ranged damage.
  • Only party members and either Orpheus or the Emperor can enter the Netherbrain's psyche (or The Unbreakable Will of the Netherbrain), so once the portal is open it is no longer necessary 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 one's entire party near the portal before completing Karsus' Compulsion. Once the portal is opened, the final fight against the Netherbain begins immediately and it is possible for it to destroy all platforms near the portal, preventing party members outside from entering.
  • While allies summoned through Gather Your Allies (Class Action) cannot enter the portal, they can be summoned onto the platforms inside.
  • The first attack each round against the Brain will cause it to use Retributive Brainquake Retributive Brainquake, which will damage and potentially Slow 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.
  • The Netherbrain will use Orb of Negation Orb of Negation to summon several orbs which deal damage at the end of the next round. These orbs will destroy the platforms beneath them, so it is important to move characters off of any marked platforms.
  • The Netherbrain must be killed quickly since every platform will be destroyed in only a couple of turns.


Achievements

A-Hero of the Forgotten Realms.jpg

Hero of the Forgotten Realms
Save the day: kill the Netherbrain and destroy the Absolute tadpoles.


A-Absolute Power Corrupts.jpg

Absolute Power Corrupts
Reign with terror: take control of the Netherbrain and bend the world to your will.


A-Sins of the Father.jpg

Sins of the Father
Claim your Throne of Blood: take control of the Netherbrain for Bhaal and break the world.


Known Bugs

  • Thrown weapons that return to the user, such as Nyrulna or 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.