Ghostbusters by Akroyd, Ramis and Columbia Pictures. Marvel by the parent company and its many artists/writers.
Dedicated to reviewer Dragonelf, who supplied the song choice. 'Iron Man' by Black Sabbath 1971
Definitely accepting song recommendations ;)
Late in the twentieth-century
On hearing that they weren't gods, Gozer the Gozerian released a burst of energy from its avatar's fingers. The Ghostbusters recovered quickly and, after chastising Ray for giving the wrong response, blasted Gozer's body into nothingness. Which turned out not to be the end of it because, all too soon, a voice was booming down from the heavens asking them to choose the form of their destruction.
Egon begged them not to think of anything, so Peter did his best to clear his mind.
Meditation techniques weren't his strong suit, so he lost himself in a guitar beat.
"DAH-dum," he hummed, twitching his fingers in time. "DAH-DAH-dum, dah-dah-dah-dah-DUM-DUM-DUM!"
"Form Chosen," boomed the voice down from the heavens.
Egon held his forehead in disbelief. "Peter!"
"What? It's a good riff."
"Yeah, but we know the song and the lyrics."
Sometime very early in the twenty-first century
"You don't have to do this," screamed Pepper Potts.
"Yes, I do," answered Tony Stark. "Closing this rift now is the only way I know the future will be safe!"
"I will," he said as he slipped his helmet down and stepped into the vortex. "I'll be in signal range the entire time. I'm now heading towards the greatest concentration of magnetic fields."
Pepper hugged the communication device close to her chest as Tony's voice crackled over it.
"I'm doing my best to correct the imbalance... No... No!"
"Tony, what's wrong? The interference is getting worse."
"Its impossible. The gold connections in my suit are turning to steel! I can't explain it, I..."
His only reply, for a time, was a long, drawn out scream.
Back in the twentieth-century
A museum piece, made of iron and lead, that had sat in the same corner for a decade or two, gathering dust, suddenly became aware of a presence in the room.
"I offer you power," the invisible energy hissed. "If you join me willingly."
"Anything," the roughly man-shaped hunk of metal said, tapping into the entity's energy to power itself. "Anything to get out of here and wreak my vengeance on those who left me to rot."
"So be it," Gozer's voice muttered as it flowed into the metal and the two beings became one.
The metal shape promptly grew to twenty times its previous size, bursting through the roof and sending priceless artifacts flying through the walls.
That was before it took its first step.
"Well, friggin' great." Peter waved his arms in frustration as they saw the destruction. "The guy in iron's here to cause us all to writhe in fear all because you guys had to supply words to my completely abstract notes, my girlfriend's still a dog, and we still need to walk down all those steps because that thing's stomping in the other direction!"
"Iron Man," Ray called from his rooftop position in the 'trap' they'd led the monster into. "We know from the song that you used to be a hero. You're being possessed by the Destroyer! You can fight this. Don't you want to be what you used to be?"
"I used to be a tool," the hulking metal boomed. "Nobody ever asked me if they wanted me to save the world. Nobody asked me if I wanted to risk being sent a hundred years into the past, where I'd sit in the corner, forgotten. You're trying to reach the man inside the suit? Well, that's just not gonna happen. How about you talk to the hand?"
The towering humanoid shape lifted one of its arms straight out in front of it. Its palm began to grow a bright blue.
"Wait?" Winston asked, turning to the Ghostbuster next to him. "That thing has energy beams?"
Back in the twenty-first century
Pepper Potts was sitting in a chair, sobbing quietly to herself, when someone touched her shoulder.
"Tony," she yelped, jumping to her feet and throwing her arms around him. "You're alive! You're naked, but you're alive! Uh..." She took a step back and brushed herself off.
"Yes," he said, grinning roguishly. "I'm okay. The suit was a dead loss though. I had to abandon it somewhere in the timestream, or risk being turned to metal myself. I'm guessing it landed around nineteen-oh-two."
"Oh... Are we going to be okay?"
"Absolutely. The transformation fused most of the circuitry so the computer system won't be able to move under its own power. It looks too much like an art piece for any scientists of the time to dissect it. We'll just have to spend some time in antique stores tracking it down and home that the computer's brain won't be too annoyed at me for leaving it in a non-functional body for so long."
Those were his last words before the first of the time storms ripped them apart.