X-Men/Avengers: Onslaught Omnibus

The emergence of Onslaught, a formidable fusion of Magneto's fury and Charles Xavier's psionic abilities, poses a dire threat to the Marvel Universe. As heroes like the X-Men and Avengers confront this powerful entity, they grapple with the sacrifices required to combat this unprecedented evil. The storyline weaves through various series, showcasing the extent of Onslaught's impact across multiple characters and teams, revealing the challenges and choices faced by Marvel's greatest heroes in their quest to save the world.