And now we come to one of the absolute toughest parts of any story — the end.
At the break into Act Three the main character(s) has made a proactive decision to go forward with a plan to fix everything that had been ruined up to this point. Looking at Blake Snyder’s beat sheet, there’s only two more beats after that — The Finale and The Final Image (aka the denouement).
The Finale is almost the entire third act, in ONE beat. So… um… what exactly do you do there?
Pretty much whatever you want. This is the part of the story where you take everything you’ve presented in the previous 3/4 (acts one and two) and use it to maximize everything you feel is important about this story.
Which is why I suggested going back and reading through the story before writing Act Three.
By this point, you have a better idea of your theme. You know your MC’s strengths and weaknesses. You know precisely why you felt the need to write this story, and you’ve gotten this far, so now you want to finish it.
This is where all your previous clues become blatantly clear to the reader. You revisit actions, dialogue, thoughts, etc. to drive home the pivotal moment of the climax where everything is set right again.
A superb example of this is in Lauren Oliver’s BEFORE I FALL. The book is only seven chapters long, but each chapter covers a full day in Sam’s life, the same day she keeps re-living. Every day she sees the same things and different things. All of these are clues to the reader, some more obvious than others, that give the ending MAJOR IMPACT. The reader is able to somewhat guess what’s coming, while still being knocked out of their seat when they get to that point. Seriously. I’m personally not super-keen on how that book ended, but I can’t deny how perfectly executed it was… and when I really think about it, it couldn’t have ended any other way and had the same effect. I just don’t like death. (and saying that someone dies at the end doesn’t give anything away, trust me)