This article contains spoilers for Marauders #14, by Gerry Duggan, Benjamin Percy, Stefano Caselli, and Edgar Delgado.
Wolverine's greatest kill will shake the entire Marvel Multiverse to the core. Logan has always been something of an uncomfortable fit among the ranks of the X-Men. It's not just that he considers himself something of a lone wolf; it's also because he simply doesn't mind killing. In his view, some enemies are best compared to wounded animals that should be put out of their misery.
However uncomfortable Wolverine's peers may be with this argument, they nonetheless appear to see the logic of it - and even the Avengers agreed, with Tony Stark and Captain America once recruiting Wolverine because they trusted him to get his hands dirty so they didn't have to. When Logan pops his claws, he cuts a bloody swathe through enemies of the X-Men and the Avengers alike, and only the toughest foes survive to take him on a second time.
Marauders #14 sees Wolverine take drastic action as part of the current "X of Swords" event. Ten champions of the mutant nation of Krakoa must go head-to-head with the ten Swordbearers of Arakko, with the fate of the entire Multiverse on the line. The duels have been orchestrated by Saturnyne, the Omnivestral Majestrix who rules Otherworld, the nexus of all realities. Wolverine doesn't like the terms - and so he changes the rules of the game. He pops his claws, and uses them to kill Saturnyne herself.
This is certainly a game-changer, and the deed is done with the agreement of Storm, who has intuited Wolverine's murderous intent. As ever, though, Wolverine's focus is purely on his own interests and those of the X-Men; he is entirely unaware of Saturnyne's significance as ruler of Otherworld and principal protector of the Multiverse. If he has succeeded in killing Saturnyne, then he has plunged all of time and space into untold chaos. Wolverine has taken down some high-profile targets before, but they all pale into insignificance in comparison to this.
But is Saturnyne really dead? She is a master at reading the future, a truth she reminded the X-Men of in this very book, and as such it's highly likely she knew what Wolverine intended to do. In fact, she was the one who named Wolverine as one of the combatants, so it's entirely possible she brought Logan here for exactly this purpose. It's already been hinted Saturnyne has a greater agenda than simply arranging a duel, and the X-Men could have just played into her hands.