What To Do?
After Bill managed to break into the real world, Dipper and the author decided to attack Bill using a weapon called 'The Quantum Destabilizer', which is the only thing capable of killing Bill Cypher. The only problem was that it had only enough charge for one shot. The author got ready, held his breath, slowly pulled the trigger...
And missed.
Dipper ran away. Bill had caught the author and disintegrated the Journals. Mable was still missing, and the town had been swarmed with creatures of horror. Later, he finds Wendy and Soos, which help him look for Mable. Eventually, they stumble across a large bubble on the other side of a cliff. They make it in and find Mable, who has been trapped in a false world she controls. They eventually manage to convince her of leaving, and with that, Dipper, Mable, Wendy and Soos all decided to go to the mystery shack. There, they found their great uncle and many creatures which the twins have met on countless journies in Gravity Falls. Dipper explains to them that in order to defeat Bill they'll need help from someone who already has experience with him, and that someone is currently trapped in Bill's lair. One of the characters taking refuge in the mystery shack is an insane inventor who was able to propose an idea. In about 2 weeks, the entire crew managed to create 'The Shaktron', which is a transformer version of the mystery shack.
Now it's time to take back the Falls.
The Final Showdown
Everyone was in position, the gears started to turn, the steam started to come off the chimney, and the ground began to shake. Then the tarp began the lift off, and from the ground emerged the Shacktron. Marching onward, the twins were telling everyone what to do, and eventually made it to Bill's Lair. There, his intergalactic friends tried to take care of them but eventually got overpowered by the sheer strength of the Shacktron. Next came Bill Cypher instead, but even he struggled to fight it. While half of the crew continued to control the mech, Dipper and his allies catapulted into Bill's Lair. When in, the group was shocked to find all of the missing townsfolk frozen, and great uncle Stanford frozen as a golden statuette. Upon unfreezing him with details unrevealed, the author explains that in order to defeat Bill, they will need to perform a ritual of some sort. Everyone necessary gets in position, and the magic starts to set in.
But there's one triangle that interrupts them.
Almost everyone has been captured by Bill, Stanley and Stanford are locked in a cage, while Dipper and Mable run away from Cypher. They're eventually caught, and in order to save them, the author has to let Bill Cypher into his mind, which will allow him to find information on how to escape from Gravity Falls. However, one inside the mindscape, it's revealed that the two brothers switched clothes, and Bill was now inside of Stanley's mind. The antagonist realizes this and tries to escape, but is cut off when Stanford commits to the ultimate sacrifice and uses the mind erasing ray gun the inventor came up with on his brother.
Bill has been erased. The world is saved. But Stanley's memories have not.
Or at least that's what would have happened, if not for Stanley's family.
When the family rejoins, Stanley couldn't remember a thing. But with Mable's persistence and a Summer scrapbook, the twins were able to fully restore the man's memory using the photos of his past.
​
And sure enough, it works.
Memory Erasing Gun
Bill's Henchmen vs. The Shaktron
Happy Goodbyes
Gravity Falls is safe once again. The Summer is coming to an end, and all that is left to do is to say goodbye to the heroes of the city. It's the twin's 13th birthday and their last day in the city. After spending the day with the friends they met in Gravity Falls, it was time for them to leave until another Summer. Stanley and Stanford finally managed to accept each other as brothers, and in doing so decided to venture out into the unknown and undiscovered land. Meanwhile, the mystery shack is run by Soos, and Wendy is still one of the two employees. Overall, everybody is happy.
And none of them can wait until the next Summer.