When did Moira break bad?

Now that the Krakoa era is done, and that vegetable utopia is rapidly receding into the history of x-continuity, I can now look back and realise that I missed a tonne of the big beats that dropped during the sprawling storylines. 

I never read the story that explained why I should give a damn about a whole bunch of bloody swords, I never really understood any of the deal with Arakkro, and I totally missed Moira's heel turn.

I always liked Moira MacTaggert - in a world of mutant mayhem, she was always just trying to help. She was often dealt a rough hand, with an obviously abusive husband, some history with the eternally unobtainable Charles Xavier and a son who couldn't control his mutant powers enough to stop killing people. But Moira was always there to help out with the science, and inject some more basic compassion

When it was revealed that her big mutant power was the ability to live her life over and over, it was the most major role she ever had, but also diminished the character somewhat. Because she wasn't just there to help because it was the right thing, she was there because it was her ultimate destiny, a fate built up over lifetimes of manipulation.

And then something happened, and suddenly Moira was a cackling villain prepared to murder Mary Jane Watson because she was an inconvenient witness. The next time I saw her, she was a full on murder robot who seemed very passionate about genocide.

It probably happened in one of the big crossovers that I skipped over, but it still seemed so jarring to see the generally reliable Dr MacTaggert start to froth at the mouth. At least all that cybernetic shenanigans give an easy out for future comic creators who miss the old and kind Moira as much as I do.