The Netherbrain is a driving force in Baldur's Gate 3's conflict, but he doesn't seem to be quite as intelligent as lore would have us believe.
The Netherbrain is the source of every problem in Baldur's Gate 3. Sure, without it the Three Dead would still be running around trying to take over the Sword Coast, and the Githyanki would probably still be ruled by a fascist dictator, but it would be a lot easier if you didn't have it. And half the country is a tadpole writhing in your skull.
As a Mastermind further empowered by the Crown of Carsus, the Underbrain should, by all rights, be able to conquer the world. The game spends two entire chapters describing how powerful Elder Brains are; Only through the powers of Orpheus and the good will of the Emperor can you survive his calling.
Additionally, anyone who played enough of Gale's quest, or listened to Raphael's deal in Chapter 3, will know how powerful the Crown of Carsus is. After all, it is enough to make Gale a god. A greater mind with this kind of power would definitely be unstoppable.
However, this is an area where the lore of Baldur's Gate and the need for good gameplay conflict. It wouldn't be very satisfying if Netherbrain shot your entire party at once at the start of the boss fight, even though he should technically be able to.
Some players are on The Baldur's Gate 3 website highlighted thisSaying that Netherbrain was stupid compared to the exact version.
One player summed it up as follows: “The supreme intelligence of the lower brain is nothing compared to the need of the story for the plot to reach the end.”
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