Warning: Spoilers for Halloween EndsMichael Myers' ability to survive in the time leading into Halloween Ends lends credit to Laurie Strode's theory about him. While Halloween Ends doesn't dive into Michael's backstory, it does hint at his almost supernatural ability to survive seemingly fatal attacks. In Halloween Kills, Laurie states that Michael seems to transcend with every kill. Her statement seemed to be symbolic in nature, but the last entry in the trilogy shows it might be literal.
When Michael stabs Doug after the cop is lured into the sewers by Corey Cunningham, he seems to be recharging after every stab. At the beginning of the film, Michael is weak. As the film progresses, and he kills more people, he becomes stronger. If he can genuinely transcend after every kill, this would explain how he has survived after being jumped and attacked by various citizens of Haddonfield in the previous films. This in turn lends credence to theories around some of his more supernatural abilities.
How Michael Myers' Sewer Survival Links To Laurie's "Transcend" Line
Following the events of Halloween Kills, Michael Myers has taken to the sewers. With his house demolished and paranoia spreading through Haddonfield, he stayed away from the public, biding his time. It is said that there have been disappearances over the past four years, with the revelation by a homeless man that Michael is the reason. These sporadic kills are likely what is keeping Michael alive. His weakened state when Corey stumbles upon him is expected due to him killing less than necessary. Michael has had to pick his spots with the town on alert and suffering from previous wounds.
Does Killing Keep Michael Myers Alive?
The question of whether killing keeps Michael Myers alive is never blatantly answered. The trilogy makes a point to reiterate that he is just a man occasionally but never fully details Michael's almost supernatural ability to survive. While he does seem to experience a jolt of life after stabbing Officer Mulaney, it is more likely that he enjoys killing. The homeless man living near the sewer helps Michael stay alive, possibly in exchange for his safety. With Corey starting his killing spree, Michael likely feels comfortable going after Laurie again. His thirst for revenge is what keeps Michael's drive to live going. This drive is highlighted in his final battle with Laurie, as no matter what she did to him, his will to kill her never faded.
At the conclusion of Halloween Ends, Laurie leads a procession for Michael by parading his dead body through the streets to show that the boogeyman is just human. The display is symbolic for the townspeople, indicating that the nightmare was over. Placing Michael Myers' body in a metal chipper signified Michael was not immortal, giving him a definitive end. This suggests that, for all his seemingly supernatural abilities, Michael Myers was still a real person with real weaknesses.