Crossover #4 ends with doctors/scientists combining superhero characters together in a Doctor Frankenstein manner.
Seen in the background is this character, who has a visor like Cyclops, Iron Man mask, Magneto’s shoulder pads, and a Punisher Skull.
Eagle eyed readers will recognize him from the back of 1990’s comics, Combo Man. Combo Man not only appeared on the back of comics, but had his own One Shot mini comic, kind of hard to find.
If you are not familiar with Combo Man, here is his Wiki from Comic vine
Rick Wilder was a normal student who happened across A.I.M pressuring a teacher named Professor Boyd into giving them a secret device that could expand the human potential. Upon being discovered, Rick ran into a room (where the device was running), dropped his comics and ate a combo. He was transformed into Combo Man. He easily defeated the A.I.M agents but they sent the Super-Adaptoid after him. Rick defeated him as well.