Ultimate Fantastic Four #23
an issue of Ultimate Fantastic Four by Marvel Comics
Issue description
"CROSSOVER"
On an world they never thought they’d visit, the fledgling F.F. find themselves hunted by the strangest enemies imaginable. And only one man can offer them salvation—the mutant master of magnetism—Magneto! The story you never thought you’d see comes to its shocking end! Part 3 (of 3)