Wolverine Explains How He Can Be Killed (For Good) | Screen Rant
Enemies of the X-Men have been confounded over the years by Wolverine's healing factor, which can repair virtually all mortal injuries, but it turns out the best authority on the subject of "how to kill the guy who can heal from any wound" is Wolverine himself. In Wolverine: Killing Made Simple (2008), Logan recalls a number of times he's died (all of them pre-dating 2014's Death of Wolverine storyline), in each case by an attack which overwhelmed or bypassed his mutant healing power in some extremely unpleasant way. In typical Wolverine fashion, he's not recounting all these deaths for nostalgia or archival purposes, he is explaining them to a young kid, for the benefit of her childlike curiosity.
The one-shot special collection of Wolverine stories opens with the self-explanatory "Killing Wolverine Made Simple," from writer Christopher Yost and artists Koi Turnbull and Sal Regla. While trussed up in an armored vehicle belonging to Nanny and Orphan-Maker, Logan makes his version of pleasant conversation with Hope Abbott (a.k.a. Trance), the Xavier Institute student whom he ostensibly is trying to rescue. At Hope's prompting, Logan lists a fairly comprehensive rundown of various ways to kill him. He doesn't go into the details of how he was reincarnated each time, but does offer insight into which deaths were most grisly, efficient, and/or unconventional, which we as readers must take on faith because he was there, every time.
Wolverine explains that he would be killed by metal poisoning, on any occasion when his mutant power is negated or removed. "Take away my powers, I'm dead. The metal on my bones, it'll kill me." He also describes the scenarios in which his fully-functioning healing power wouldn't be enough: Magneto launching him into the sun, being beheaded by the magical Muramasa blade, attack by "reality benders" (presumably referencing Proteus or an Infinity Gauntlet-wielder). At this exact moment, he's concerned that Nanny will de-age his body to that of a 13-year old, leaving his metallic bones intact, in which case his adolescent flesh regenerating around an immutable adult skeleton will cause his grotesque demise. The premise of this may seem questionable (was short-statured Logan's 13-year-old skeleton irreconcilably different from his adult-sized frame?) but the mental image is enough for Hope to insist, "Just stop. I'm going to barf."
Hope's preference notwithstanding, Wolverine outlines all the major ways his healing factor can be outdone, from his personal experience. The reliable methods seem to be: 1) Instant vaporization of every cell in his body, as famously depicted in X-Men #142 (the original "Days of Future Past" story arc) when a Sentinel blasts all but his skeleton into nothingness. 2) Magic weapons, which circumvent whatever physics Adamantium is based on. 3) Cosmic reality-warpers which can break sub-atomic bonds. 4) Suppression or modification of the healing factor itself, which is surely the most ironic way to do the fatal trick. Logan also mentions the time-travel scenario in which his very existence could be cancelled by someone travelling to the past, but this is not a problem unique to Wolverine, if we're being honest.
For those seeking a Greatest Hits collection of Ways To Slay Wolverine, Killing Made Simple is essential reading, intertwining Wolverine's own grim hypotheticals with events which have "actually" occurred in Marvel comics. Possibly, Logan has read every issue of Marvel's What If?, in which imaginative means of ending the world's most-indestructible Canadian is a popular trope. None of this addresses the question of how much food (or beer) Logan must intake to keep his cells regenerating at their superhuman pace, but perhaps that's a mystery for another time.