The Real Story Behind When DC Characters Appeared In Monthly Marvel Comics
6. Onslaught!
The titles Liefeld and Lee were going to take over would need to be relaunched. As such, the creators and publisher took a "ground-up" approach to retool these characters for the modern era. This approach became a prototype for Marvel's much more successful Ultimate line years later.
In an attempt to draw the industry's attention, the rest of the Marvel Universe found itself thrust into an already planned X-Men event called Onslaught, where a nightmare fusion of Charles Xavier and Magneto would rise and threaten the entire world. As always with company-wide crossovers, the publisher made outrageous claims, promised "real stakes", and trotted out the old "Marvel will never be the same again" line. Only this time, it would be more accurate and controversial than even the most jaded fan could know.
In the act of self-sacrifice, the Avengers, the Fantastic Four, Doctor Doom and the Incredible Hulk would perish in stopping Onslaught. Or, more accurately, they would be transported to a pocket universe created by Franklin Richards, the mutant son of Reed and Sue Richards.