- Script:
- Chris Claremont
- Pencils:
- Dave Cockrum (page one); Tony DeZuniga
- Inks:
- Tony DeZuniga
- Colors:
- Andy Yanchus
- Letters:
- Annette Kawecki
- Genre:
- superhero
- Characters:
- X-Men [Professor X [Charles Xavier]; Cyclops [Scott Summers]; Phoenix [Jean Grey]; Storm [Ororo Munroe]; Wolverine; Colossus [Peter Rasputin]; Banshee [Sean Cassidy]; Nightcrawler [Kurt Wagner]]; Moira MacTaggert; Warhawk [Mitchell Tanner] (villain)
- Synopsis:
- The X-Men have to fight off an invader in X-Mansion who has been sent to test their abilities.
- Reprints: show reprint note before migration
Fill-in originally planned to be X-Men #109, as explained by Claremont in the letters page; Last page shows Wolverine wearing gauntlets out of which his claws pop (they were originally intended to be part of his costume and not implanted in his skin).