There's A Secret Baldur's Gate 3 Ending That Lets You Haunt The Epilogue Party

thegamer.com:

Baldur's Gate 3 has a lesser-known ending for dead player characters, letting you haunt the epilogue party. To pull it off, you have to get Gale to sacrifice himself at the end to destroy the Netherbrain, but without teleporting his friends to safety. If you do this, you'll die, but Withers will still invite you to the big meet-up in the epilogue.

Instead of walking around, mingling and catching up with everyone, you'll appear as a spectre - essentially a ghost that can't speak or be seen by other characters. While this makes for a fairly dull party, you can get up to some ghostly shenanigans, and scare the living daylights out of the survivors of your campaign.

As seen in this video from TikTok user tinker.tessa, the dead player character can pick up and throw items, alerting all of your friends to your undead presence at the party. Few characters realise that it's you, and understandably, freak out. Good ol' Jahaira immediately picks up on your antics though, clearly amused that you're using your return from death to prank everyone.

If you were planning to have Gale save the day in your playthrough, just make sure he's agreed to it during the Emperor/Orpheus confrontation. If you've set it up correctly, Gale will offer to blow himself up before you take on the final boss, skipping it entirely.

I tested this out, and a surprisingly easy ending to achieve. Instead of telling Gale to go boom before you make your way to the final boss, you have to wait until the whole party is on the Netherbrain. Then, during the fight, just select the orb bomb from Gale's spells during his turn, and you'll have a quick conversation with him where you decide to go down as a team - and take the Absolute down with you. You'll get the usual