Edited by Marv Wolfman & Len Wein
Pocket Books, September 1979
First Printing, $1.95 cover price
Cover by Dave Cockrum
Unfortunately this novel wasn't an actual team-up of all these Marvel heroes, but four stand-alone stories featuring The Hulk, Daredevil, The Avengers, and the X-Men.
Written by Jim Shooter, Len Wein, Mary Jo Duffy, and Kyle Christopher.