X-Men / Avengers: Onslaught #2

This second volume continues the massive crossover event that saw the psychic entity Onslaught, born from the merged psyches of Professor X and Magneto, threaten the entire Marvel Universe. Collecting the concluding chapters of the saga, it features the combined forces of the X-Men and Avengers making their final stand against the nigh-omnipotent villain, leading to dramatic sacrifices and a major status quo shift for both teams. Key issues include the climactic battles from titles like X-Men, Avengers, and Fantastic Four, culminating in the heroes' desperate gambit to stop Onslaught's world-ending rampage.