Baldur's Gate 3: Should You Free Orpheus?

MAJOR SPOILERS FOR BALDUR'S GATE 3 FOLLOW

As you travel through Baldur's Gate 3, and reach Act 3, you'll meet with a key figure in the entire game for the first time, and he'll try and convince you to leave a hostage that he has held where he is for your sake, but there's more than one option here. The question is: should you heed the warnings of The Emperor, or should you free Orpheus?

Should you free the captive Githyanki?

First of all, in order to even think about freeing Orpheus you need the Orphic Hammer, which you'll find inside the Hosue of Hope. Once you have that and you reach the Astral Plane for the final time in the game, you'll be able to help free Orpheus. Alternatively, you can take a deal with Raphael to give him the Crown of Karsus in exchange for access to the Orphic Hammer, though the implication is that he has nothing good planned for the super-powerful artifact. 

Freeing Orpheus means that The Emperor will leave and join forces with the Elder Brain, meaning you'll have to fight him in the final boss battle. Orpheus is an extremely powerful ally to have in his place, however, and you can choose whether he becomes a Mind Flayer or you become a Mind Flayer to wield the stones. Alternatively, Karlach can become the Mind Flayer as she believes it might save her from suffering the ultimate fate of having to go back to Avernus and fight her way through hell.