Cover pencils credit changed to Jack Kirby by Mark Evanier, who says (via the GCD Errors list, August 2009) "As far as I know, Kirby never did layouts at Marvel for a cover where someone else did the pencils." Original indexer had "Jack Kirby (layouts); John Romita (pencils)."
The story offers little in the way of explanation as to exactly why an immortal from Asgard is trying to conquer the future earth.