This new Iron Man 3 featurette explains what the nanotechnology serum Extremis is:
Iron Man 3 – Extremis
“Tony Stark (Robert Downey Jr.) uses his ingenuity to fight those who destroyed his private world and soon goes up against his most powerful enemy yet: the Mandarin (Ben Kingsley).”
So basically Extremis is a nanotech version of the serum that created Captain America… Would a botched injection of Extremis create some kind of Hulk then?
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