Tales of Suspense (1959) #49
Published Jan 1964 by Marvel. First X-Men crossover (same date as X-Men #3 - January, 1964), plus first Avengers crossover (without Captain America)
Iron Man story, "The New Iron Man Meets the Angel!", script by Stan Lee
Pencils by Steve Ditko
The Angel is affected by an atomic test done at one of Stark's weapons plants. His personality is altered and now he wants to join the Evil Mutants; The X-Men call the Avengers for help but only Iron Man is available.

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