The X-Men #31

The X-Men are given a weekend off and head out for some fun. Cyclops and Angel visit Jean in college and find her engaged with brothers Ted and Ralph Roberts. Ralph, who used to work for Tony Stark, takes them all to his lab where he puts on his new Cobalt Man suit to impress his brother. Going a little batty, Cobalt Man wrecks the lab and heads out to Stark Industries to confront his old boss. The X-Men assemble to battle him before his suit becomes radioactive and blows up.