5
It was only twenty HYDRA men getting too close to S.H.I.E.L.D, Tony should've been able to take care of it. Hell, he was so bored he'd even volunteered to do it.
But, when they saw Tony, each of them swallowed a pill and their muscles unnaturally ballooned, and suddenly there were twenty ugly as fuck superpowered soldiers. Tony was 75.62% sure that it was somewhat based off of the super soldier serum, or someone attempting to recreate it. Even in the suit, their punches hurt like a bitch, and soon he was just attempting to hold his own.
One well aimed fist near his torso and he finally faltered, blood dripping from his mouth. Another tore off his faceplate, discarding it to the side like it was trash. The final blow was near his arc reactor, and he barely registered the sickening crunch. He flew into a nearby wall, immediately sliding down to a crumpled heap.
By then he was out cold. The other Avengers were now on the scene, too late. They cried out to him, tried to wake him with words. But nothing worked, and they couldn't get close enough to survey the damage on him. Soon the battle was over, the Hulk, Thor, and Steve too much for them, as many as there were, to handle.
When they see Tony there, none of them move for a good three seconds. It was Steve who made the first step. "Tony!"
Tony just laid there still, the light of his arc reactor flickering like a dying bulb.*
They call Pepper.
"Tony keeps a spare in Phil's office. On the top of the bookshelf, there's a white box ," she tells them, her voice betraying her calm facade. "That's it. You don't have long, hurry!"
They do, and a very naked but very unashamed Bruce Banner installs it, and the color in the Stark's face begins to return. He opens his eyes only minutes after.
They laugh in relief and Natasha tells Tony he's no longer allowed to do missions while bored and he just smiles.