Mabel was in the sporting goods store with Grunkle Stan, Soos, and Wendy. They each had shoulder pads, knee pads, and elbow pads. Luckily, there was heavy looting going on so they didn't have to pay for them.
"Mabel...you are aware there's a possibility that Dipper may not survive the battle, right?" said Stan.
"I know..." said Mabel.
"Well, I happen to know there's a chance he will survive," said a voice from behind them.
Mabel, Stan, Soos, and Wendy turned around and saw Tony Stark behind him.
Mabel: OH MY GOD! You're Tony Stark!
Tony Stark: And you must be Mabel Pines. Pleasure to meet you too Soos, Wendy Corduroy, and Stanford Pines. Listen, we need to talk.
"What, are you from the Army? Because I can't help you if that's the case," said Stan.
Tony Stark: No. I work for Stark Enterprises and the SHIELD. Follow me.
Stan shrugged and walked away with Tony. When they were out of earshot of everyone, Stan spoke up.
"So, what do you need to talk to me about?" he asked.
Tony Stark: Me and Star-Lord arrived in town cause we couldn't take the excessive damage that's being caused thanks to Galvadouche. I mean, Galvatron to be exact.
"Jeez! I didn't know you could join the Order at this age...wait a minute, who's Star-Lord?!" said Stan.
Tony Stark: Star-Lord is a member of a secret operation led by Optimus Prime. OK you know what I'll just cut to the chase here, kill Blitzwing. I know this Pine Tree guy's inside him, but that's the only way to stop this madness and a way to make Galvatron and the others retreat.
"But, you don't understand-" said Stan.
Tony Stark: Stan, I'm sorry. But what's done is done.
Stark leaves an awkward Stan. He then gets on his ringing phone as Star-Lord is calling him.
Tony Stark: Star-Lord.
Star-Lord: You gave him the word?
Tony Stark: Indeed. How are things on your hand?
Star-Lord: I got Pentacle and Broken Heart with me and the others.
Tony Stark: Good work Quill.
Back with the Pines group...
Stan returned, looking sad.
"Stan, what's wrong?" asked Mabel.
"What? Nothing's wrong...nothing at all," said Stan.
Galvatron: Attention Shooting Star, Moon, Question Mark, and Ice! I've had enough of you four! So, I'll tell you what: Meet Blitzwing and the others in Circle Park in 30 minutes. FOR MY ERA BEGINS ONCE YOU ALL DIE!
Mabel, Grunkle Stan, Soos, and Wendy entered Circle Park. Waiting for them was Dipper Cipher.
Wario: Welcome to the arena for the last fight of your lives!
Stinger: Really Wario? Ringmaster Entrance?
Wario: It was an option man.
"To be honest, this is going to hurt me a lot more than it's going to hurt you," said Mabel.
Blitzwing: No. It'll just hurt you.
Blitzwing fired a blast of energy at Soos, who barely got out of the way in time.
Wario: Look Out Bitch!
Wario fired a blast at Wendy, sending her flying into a tree.
"Mabel, I hope you have a plan of attack!" said Stan.
"I have a plan: attack!" said Mabel.
Suddenly, the Dipper part of Blitzwing took hold again, causing another internal struggle. He looked around in horror as he saw Wendy barely conscious and Mabel and Stan aimed at by Wario and Waluigi.
"M-Mabel? W-Wendy…?" said Dipper.
Suddenly, with a single glance at it, Dipper somehow knew the MP3 Player could free him. He started to forcibly make his way towards it.
"You won't destroy my friends and family Blitzwing!" said Dipper Pines.
Blitzwing (Noticing Dipper's prescence): WHAT!? IMPOSSIBLE!
"GET OUT OF MY BODY!" yelled Dipper Pines, jamming the MP3 Player's headphones into his ears and putting on the synthesized music.
Almost instantly, Dipper felt raw energy building inside of him. After two seconds, it exploded out of Dipper in a tremendous blast. Mabel and Wendy barely got Grunkle Stan undercover in time.
Blitzwing: NOOOOO!
An Explosion occurred. Blitzwing was seemingly destroyed.
Wario: WHAT THE HELL?!
Stan, Mabel, and the others looked in joy as Blitzwing was defeated and seemingly Dipper was freed. However, Blitzwing came out of the smoke furiously in full battle mode, much to the shock of Stan, Mabel and Wendy.
Blitzwing: FOOLS!
Blitzwing makes a huge blast, knocking out Mabel and Stan in the process.
Blitzwing: DEFEAT ME!?
Blitzwing makes another huge blast, knocking out Wendy and sending her flying into a building.
Blitzwing: DESTROY ME!?
Blitzwing makes yet another huge blast, destroying a building nearby.
Blitzwing: I WILL SHOW YOU DEFEAT!
Blitzwing flies off while Wario and Waluigi take off in their flying Motorcycles. Stan tried to stop them, but couldn't due to the pain he suffered from Blitzwing.
Galvatron and Lockdown are watching from the cliff above.
Galvatron: And so the third phase begins. Decepticons, roll out.
The Decepticons, Galvatron, and Lockdown transform and take off. Robbie sees this from the hospital and goes to meet up with several news crew members, who are currently reporting the incident.
Robbie: Listen to me! Don't you have any idea what's coming for us!?
Blitzwing and the decepticons take off.
Blitzwing: I. Am. FIRE. I. Am. DEATH.
Blitzwing and the other decepticons escape the ruins of Gravity Falls and head toward their next target city. Stan watches this in complete horror.
Stan: What have we done!?