All the prompts I've seen saying to tie up my loose ends were misleading considering I could still go back and finish things. Going to the mountains or the gith creche, entering the under dark and the shadow cursed land... The only one with slightly different verbiage was when I entered the prism, and that was the only one that actually made it where I couldn't come back from shit.

It was a bit annoying, because up to that point I'd been told the same thing with different words and it didn't mean jack, so I figured this time wouldn't be different and it ended up killing a ton of people I know I can save. 😩

It didn't mention the act at any time, and from what other players have been talking about I am pretty fucking sure I got the ending this speedrunner did because the game basically ended at Ketheric my first run.