Yeah, and this is basically impossible to display in a game (for the player).
Ha!

Not at all, my friend ... not at all.

You see there are lots of games (especialy if you like certain themes, lets say it this way) ... where your protagonist is basicaly lost in the process ... same situation could happen here.
Lets imagine together:
Instead of transformation scene we got ... where our character simply squirm in pain (is suppose) and then illithid stands its place ... we would make something entirely new, and unique in this game.
We would ... change our perspective to first person!
Imagine:
You click on that dialogue option, offering yourself to turn ... and then you see your character squirm and being in pain ... next second, you are no longer looking AT the character, you are looking at The Emperor / Orpheus trough your character eyes, still squirming ... and the sight fades to dark in meere seconds, all you hear there is Narator telling something like:
"
Too late you realize this is end of your journey, too late you understand true weight of your decision, but there is no going back, not anymore ... your body, your mind, even your soul, everything has ben lost in the process ... the ultimate sacrifice."
Then we let this nothingness for a second or two to sink in ...
And once again in first person, we would trough eyes of our character see in flash of light The Emperor / Orpheus abowe us ...
Narator telling something like:
"
You were BORN anew! Yet you rememer your own death. You wonder for a second if is this really you, or just something that remembers you?But there is time and place for such questions, and its not here, nor now ... you have work to do.And then you get that scene, where newborn Illithid is standing up and materializing that weird armor.

Tada!
Entirely possible as you may see.
