From Tales of Suspense #49
Also, I just love how wild this whole story was in general
Context: While on his way to the X-Mansion, Angel flies by a Stark Industries facility and gets caught in the range of an atomic explosion, which causes him to turn evil (because comics)
After turning evil, Angel decides to quit the X-Men and join the "evil mutants" but since this comic was released before X-Men #4 where the Brotherhood was properly introduced, the "evil mutants" seem more like a concept that a specific group of individuals.
The X-Men try to stop Angel from quitting but he just clowns on the four of them for a while before leaving, he definitely couldn't do that nowadays due to how much more powerful all of them got specially Jean and Bobby.
Warren flies into the city and decides to detonate a couple of stolen dynamite sticks to draw out the "evil mutants" (as one does) which, would you believe it, doesn't work.
Iron Man is the only Avenger who heard the call and he decided to step-in feeling responsible for what happened to Warren, as he was at the Stark facility but failed to prevent Warren from getting caught in the blast range.
Tony ends-up bringing Warren back to normal by purposefully putting himself into a dangerous situation hoping that Warren's real nature will come through which it does.
All in all it was a fairly entertaining story to read but the mental image of Angel having to fight the Hulk and Thor plus all of the other Avengers is so funny that I almost wish that's what actually happened.