Well, the curious thing here is chance. Polaris's powers go nuts for a little while, so they stick her next to Magneto, they finally track down Longshot and stick him next to Magneto. You have everything you need there for Magneto's break.
But the question is, whose probability powers were setting up these events? Wanda's, or Longshot's? Or, did Magneto have a larger plan himself that he somehow put in action.
And curiously, I see some distinction between Wanda's and Longshot's powers here. Longshot is purely luck, where Wanda seems to be the mutant equivalent of the probability drive from Hitchhiker's guide to the galaxy.