Wilson pencils confirmed by the artist. Possible Giacoia inks per Nick Caputo. Previous indexer credited Herb Trimpe with pencils and Fred Kida with inks.
Mastermind is not the X-Men villain.
Letters from Francis Halligan, Bart Strange, Colin Curren, and C. Parkes & L. Pearce.
o.t. "Behold the Savage Sky" (splash page not by Steranko).