12. The Brotherhood Vs Cyclops' X-Men, Wolverine's X-Men, Young X-Men & Future X-Men (Wolverine and The X-Men #37)
Man, this is a complicated one. Part of the "Battle of the Atom" event, Wolverine & The X-Men #37 was the penultimate (and ninth out of ten) part of the arc. It saw an epic battle which pitted several teams of future, past and present X-Men fighting the future version of the Brotherhood (trying to explain how this fight came to be without writing a dissertation would be like trying to pick a lock with freshly cooked spaghetti, so let's just stick to describing the fight itself). Although this story as a whole was pretty poor (it felt stretched out and unevenly paced, and seemed hastily produced, with editorial slips, story inconsistencies and rushed artwork), this fight was awesome, as it saw two good Beasts fighting against an evil Beast, Wolverine fighting his shape-shifting son (whom he previously didn't even know he had), two Cyclops' going at it against each other, a Jean Grey versus Jean Grey bout, two versions of Iceman (one of whom, from the future, has an awesome wizard beard) slugging it out and missiles from S.H.I.E.L.D helicarriers firing all over the place (future Colossus also has an awesome metallic moustache, for the record). Awesome action and simply great to see so many mutants - and so many different versions of the same mutants - in a single on-panel battle at the same time.