After altering reality so mutants were the dominant race, the Scarlet Witch then changed reality again, this time attempting to rid the world of the mutant gene, by casting another spell, "No More Mutants", either de-powering or killing the vast majority of mutants.
That event occurred at 11:15, a Tuesday morning in New York City, or off-coast of Callao, Peru at 3:00 PM in the afternoon of November 2nd.
Overview[]
At the time of the Decimation, it was first estimated that 91.4% of the world's mutant population lost their powers overnight. The US Government estimated a number of 198 mutants, cataloged, but acknowledged that there were a few thousands, around 300 individuals who were recognized as mutants, and Tony Stark admitted that a low estimate had been produced. Dani Moonstar stated that there were 198 known mutants, but others had remained off the grid until then, including Jonas Graymalkin or Leon Nunez, but also known mutants, like the "199th mutant", off the record of the 198 as part of a deal with the government, or Wiz Kid who hacked into S.H.I.E.L.D.'s database.
The 198/"less than 200" estimation was although often used as the correct number, as well as "9/10" or "two hundred remaining mutants". A Cerebro estimated a decrease of 91.4% of the world's mutant population in the moments after the M-Day, when Tony Stark stated (after the Civil War) that over 99.99% of the mutants were. It was often stated that "90%" or "over" of the mutants lost their powers.
It was stated that a million mutants or more were depowered on M-Day. This tallies with a rounding up of the 986,618 figure.
In the sole Xavier Institute, the mutant students count went from 182 to 27.
Immediate attacks[]
The Sapien League took advantage of the situation by attacking the mansion and any mutants attempting to reach it.
The X-Corp office of Paris was bombed, and Cyclops consequently dissolved the organization.
The 198 at the Institute[]
The Xavier Institute became a haven for those who still had their mutant powers, many of them attempting to escape persecution. Against the wishes of Institute professors Emma Frost and Scott Summers, the government assigned Sentinel Squad O*N*E to protect the mansion and its inhabitants.
Mutants at the Institute rallied around the number "198", an early government estimate of how many powered mutants were left in the entire world.
The Ghoul[]
Reporter Sally Floyd interviewed a number of depowered mutants for her Mutant Diaries report. However, a serial killer calling himself the Ghoul murdered several of those whom she interviewed, leaving "Not enough died" as a marker. The Ghoul was eventually killed in an explosion during an attempt to capture him by the X-Men. Given the nature of his teleportation powers, it's possible that the Ghoul survived.
M-Day Energy Effects[]
When Scarlet Witch depowered mutants, she did not destroy the energy those mutants possessed. Instead, the energies got expelled from their bodies. While passing some orbiting rocks, the energy awakened a dormant Vulcan (who was able to survive in space due to being fused with Darwin). This massively boosted Vulcan's powers. Eventually leaving orbit and entering the atmosphere, the energy was absorbed by the Collective, turning him into an immensely powerful and dangerous being; the energies later got dispersed into the Sun.
Mutant Town[]
X-Cell, a group of former mutants who blamed the United States government for losing their powers, began a terrorist campaign. With the overwhelming majority of Mutant Town's residents now depowered, the label quickly began to lose all meaning.
Onslaught[]
Somehow, Onslaught was brought back to life, and chased Franklin Richards to Counter-Earth.
Salem's Seven's return[]
All dead, banished, or inanimate, the Salem's Seven were all returned, including Brutacus who is part mutant.
Effects[]
Effects on mutants and X-Gene[]
The X-Gene was erased from the Depowered Mutants, without any trace. Depowered mutants were detected as Humans.
The Decimation effected the DNA of every mutant, even when separated from its source: Mutant Growth Hormone (MGH) provided by depowered mutants was rendered useless.
Astra managed to create a seemingly powered clone of the Blob despite the fact that the original had been de-powered.
Reversing the Effect[]
While the M-Day effect was initially thought to be irreversible, some methods proved more or less effective in restoring mutant powers.
Celestials[]
In concordance with the High Evolutionary, Magneto was able to construct a machine to restore his powers, using the Dreaming Celestial and the product of what they called "a Celestial lobotomy". The machine however, was not only nearly impossible to construct but extremely dangerous. The process worked, and Magneto regained his mutant powers at the cost of the machine itself.
Apocalypse managed to restore the powers of Polaris (depowered by M-Day) after turning her into a Horseman. It was believed that Apocalypse simply gave her powers similar to her old ones through other means, but he seemingly managed to re-activate Polaris' X-Gene.
Reality Manipulations[]
After one of Legion's rogue personas, dubbing itself Moira, altered reality to create a world of constant war and struggle where he was a hero, some aspects of this reality bled through into the real world after Legion restored it. One of these aspects were the powers of Chamber. In this reality created by Legion, Chamber once again had his mutant powers in their old state, and upon returning reality to it's original form, Chamber kept his restored powers.
After falling into the M'kraan Crystal and drifting into the White Hot Room, Professor Xavier regained his telepathic powers upon emerging.
Wanda Maximoff was able to reverse the M-Day effect on one mutant, Rictor. After losing the source of her enhanced powers, the Life Force, however, Wanda was unable to reverse it for anyone else.
Hope Summers and Phoenix[]
The return of mutant messiah Hope Summers to the present triggered the first activated mutations since her own and M-Day. It is believed that this, along with Hope's unique ability to stabilize these mutants, were an extension of her relationship with the Phoenix Force.
The Phoenix Force travelled to Earth to claim Hope Summers as its host in order to reverse the Scarlet Witch's curse. It did so successfully, after Hope used its powers to re-ignite mutations across the world. This only caused new mutant births however, and did not restore the powers of previously depowered mutants.
The Five[]
After the founding of the mutant nation of Krakoa, a group of mutants known as the Five were created, composed of Hope Summers, Proteus, Tempus, Egg, and Elixir. The Five were tasked with resurrecting mutants who had died prematurely. The Five able to revive depowered mutants with their powers intact, presumably in part due to Proteus' reality warping powers.