Everything changes for the Children of the Atom and Earth's Mightiest Heroes! Behold the psionic force of nature known as Onslaught - but what dread foe could terrify the unstoppable Juggernaut? As Cable battles Post, herald of the oncoming doom, Nate Grey faces a ghost from his past - and Onslaught gathers his forces! The Avengers join the X-Men to work out a battle plan, but could the answers lie with finding Magneto? And Charles Xavier has a troubling proposal for the Fantastic Four. But when Onslaught's identity is revealed, who will be the traitor to the cause? Collecting CABLE (1993) #32-33, UNCANNY X-MEN (1981) #333-335, X-FORCE (1991) #55, X-MAN #15-17, X-MEN (1991) #53-54, X-MEN UNLIMITED (1993) #11, ONSLAUGHT: X-MEN, AVENGERS (1963) #401 and FANTASTIC FOUR (1961) #415. Rated T+