Everything that happens in Baldur's Gate 3 leads up to one final moment: a confrontation with the Netherbrain. This Elder Brain, also called the Absolute, has evolved thanks to long contact with the Crown of Karsus and become far more dangerous than any other Elder Brain in the illithid empire.
Baldur's Gate 3: Netherbrain Boss Guide
The final boss of the game is a tough fight, but a little preparation can make it much easier.
