Hi! I've seen you've done some good work on the Decimation page. I have myself corrected a few errors, that were already scattered in the pages:
Luna is the only "mutant" (quite a particular case) repowered by the mists. Pietro lost his terrigenesis powers and was repowered without explanation (I would say it's Wanda but no proof)
I don't know for Sunfire (but I have to check he was really depowered at M-Day, after having been depowered by Rogue), but Lorna's been confirmed X-Gene positive in some X-Men Legacy issue (when they found back Ariel). (Someone said that Sunfire was part of the Collective => depowered; but others have said that he wasn't. And I can't manage to find that issue back. Regarding to that fact, he has his place in the article or not; and if he wasn't depowered on M-Day, so Apocalypse seemingly restored his X-Gene)
I wished to know if you had an idea about how work about the M-Day/Decimation page: I've split the main article Homo superior into sub-pages
Mutant History (still nothing), and with the high-lines still on the page: Origin, Genosha Massacre, M-Day, etc
M-Day : And that's where I need help, to restructuring the article in biological, historical, consequences, etc points of view.
The problem is that for now, the information about the M-Day are scattered on at least three major page: Decimation, Depowered Mutants and Homo superior. For examples, I have corrected your adds, but those are already on another page. The idea would be to link the articles in a clever way that I can't figure for now. (As an example, I was first intending to list the depowered and repowered according to the M-Day as a main category, but I haven't managed to do it well.
Actually, the return of Quicksilver's powers was detailed in X-Factor: The Quick and the Dead. While in jail, Quicksilver begins hallucinating various important individuals in his life and according to his hallucination of Layla, the Terrigen Crystals did "their job and [he doesn't] need them anymore". After seeing a woman about to be murdered, Quicksilver finds his powers have returned, and he proceeds to save her.
As for why the mists worked for him and no one else is a good question. His initial exposure to the mists produced the same results as everyone else, the return of an enhanced version of his powers. Perhaps the fact that the crystals were imbued into his body, or that he constantly channelled their energies onto others, is responsible for the return of his ordinary powers. It's not a very clear explanation, but all we've been told is that it's because of the crystals.
As for Luna, she was born without an X-Gene, meaning she was never a mutant in the first place. Quicksilver was always insistant about exposing her to the mists to give her powers, but Black Bolt and Medusa refused because of the dangers associated with exposing someone that's only half-Inhuman to the mists. So Luna was never "re-powered", just "powered" when Quicksilver took matters into his own hands.
Thank you for the confirmation that Polaris' X-Gene returned. I was a bit hazy on whether Apocalypse actually found a cure or simply recreated her old powers through another method. As for Sunfire, if he wasn't de-powered by M-Day, he might as well be left out of the article, since it's just a list of reversals of the M-Day effect.
I'll take a look at those pages. I suppose the best way would simply be to only give a quick overview about M-Day on other pages, and simply re-direct to the Decimation page.
Concerning Quicksilver, the Dark Reign Files indicated that he recovered "mysteriously" his powers, after talking of his "pathetic" attempts to restore. What Layla Miller says is that the mists made their job, which could mean anything, coming from Layla, as allowing Rictor to be protected from the Isolationist and preventing the extinction of mutantkind. It seems really unsure in that situation to state that Quicksilver recovered his powers from the mists, after having lost his terrigenesis powers.