Hotcharokey posted the following synopsis/character list describing the issue:
Published in 1990, but it looks to occur earlier -- at least by the X-Men-related clues I see: a standing Professor X and mohawk-Storm place this between UX #181-200, 1984-1985.Mrrungo-Mu and the Enslavers invade the Earth and capture all of the Earth's heroes. In order to ensure his hold on the Earth, Mrrungo-Mu orders the strongest and most powerful heroes (Colossus, Doc Samson, the Hulk, Rogue, She-Hulk, the Sub-Mariner, the Thing, Thor, and Wolverine) be brought to him on board his spaceship and humbled before him. The Silver Surfer comes to the Earth's rescue, freeing the heroes and defeating the invaders. Grateful to the Silver Surfer, the X-Men (Professor Xavier, Cyclops, Storm, Nightcrawler, Wolverine, Colossus, and Rogue) and other heroes (Ajak, Black Bolt, the Black Knight, the Black Panther, Cannonball, Captain America, Captain Marvel, Crystal, Daredevil, Doc Samson, Dr. Strange, the Falcon, Gorgon, Hawkeye, Hercules, the Human Torch, Iceman, Ikaris, the Invisible Girl, Iron Fist, Iron Man, the Jack of Hearts, Medusa, Mr. Fantastic, Moon Knight, Powerman, Quicksilver, the Scarlet Witch, Shaman, Shalla-Bal, She Hulk, Snowbird, Spider-Man, Spider-Woman, Starfox, the Sub-Mariner, the Thing, Triton, the Vision, and the Wasp) gather on top of the Baxter Building to thank him.
Notably, the Surfer is free -- the barrier around Earth doesn't imprison him. Does that work in 1985?!