First seen in: Iron Man Vol. 2, Issue #1
Stemming from the "Heroes Reborn" comic storyline, the Prometheum Armor only came into existence in a 'pocket universe' detached from our own. After killing the first test pilot, the armor was scrapped until Stark was ravaged by the Hulk's first episode.
That origin story would need to be rewritten to fit Marvel's current movie universe, but it would be worth it.
The Prometheum Armor puts an end to managing the suit's power reserves, or fears the charge will 'run out' due to massive exertion. Rather than relying on Tony's chest-mounted arc reactor, the Armor absorbs Beta particles from the earth's atmosphere, and - through science - produces enough energy to power the suit.
Once the energy is absorbed by the suit's many components and on-board computer systems, heat (channeled through the many cables and tubes that compose the under-layers of the armor) is vented in the form of superheated plasma via the two large ports protruding from each shoulder, as well as the hands and knees. Whether that plasma is released into the atmosphere, or the face of an enemy is up to the wearer.
The technology doesn't stop there: Prometheum is equipped with tractor beams, nanobots that can be injected into the bloodstream to provide first aid, and the ability to turn invisible. We don't know what fights lie in Tony's future, but we're confident the Prometheum Armor could handle just about anything.