10 X-Men Graphic Novels You Must Read Before You Die
6. Mutant Massacre
This 1986 crossover event was written by Chris Claremont and Louise and Walter Simonson, and illustrated by John Romita Jr, Walter Simonson (pulling double duty here), and Sal Buscema, and if that doesn't tell that you really need to read this book, then nothing will.
When the Marauders attack the underground-dwelling Morlocks at the behest of Mister Sinister, it takes the combined efforts of both the X-Men and X-Factor to stop them being completely wiped out. But this is not the whole tale.
Both X-Men and X-Factor suffer major injuries. Angel is pinned to the wall, suffering major damage to his wings that eventually leads to them being amputated, Shadowcat's phasing ability gets so messed up it almost kills her, and Nightcrawler is left in a coma after getting his ass handed to him by Riptide.
Yet, the most important part of this story wouldn't be revealed for a long time after, and that was that Gambit was the one responsible for recruiting those involved in the attack for Mister Sinister.