Once the Ultimate Boon has been achieved, the antagonist chases after the Hero or a big final fight. In film this is the big, exciting climatic piece.
It’s either a fight or a flight. The Hero goes head to head with the villain. A chase with the enemies in hot pursuit or reversed and the Hero is chasing the villain. How many romantic comedies end with the guy chasing the girl before she gets on a plane to Paris or running in the rain to her house.
Like all the stages in the Hero’s Journey it’s not a literal magical flight.
Star Wars – The assault on the Death Star
The Avengers – The fight over New York
Toy Story – Buzz flies into Andy’s car after defeating Sid.
Avatar – Huge fight in the air and on the ground between the Na’vi and the soldiers.
Magic – Impressive, wondrous, explosions, boom
Flight – Chase, pursuit, run, fight,
How to use it in your writing
A ticking time bomb of some sort adds to the urgency.
Make it as big as possible as the world will allow.
It can be a fight, a chase or both.