This seems like a big deal.

This April, The Avengers and the X-Men—the two most popular franchises in comics history—go to war! Marvel is proud to announce AVENGERS VS X-MEN, a landmark 12-issue pop culture event bringing together the world’s greatest super heroes—Iron Man, Captain America, Thor, Hulk, Black Widow, Spider-Man, Wolverine, Cyclops, Storm, Magneto and more—for an unforgettable battle beginning in April 2012.

Who wins? Read the whole story linked above from Marvel and get the inside scoop.