Our entry in to this from New Mutants is Magma, who has been captured by the High Evolutionary's Purifiers (not to be confused with Stryker's Purifiers, obv). They want to stop her being a mutant, on grounds of public safety, and frankly they have a point, as it turns out she had gone spare after the events of New Mutants #64, having had a severe case of reverse culture shock.
Amara's dad complains to Emma Frost; who then summons the Inner Circle of the Hellfire Club. Including Magneto, who specifically forbids the kids to leave the mansion while he's gone. They arrive at Wyoming before he does. They've got Bulk and Glowworm, too, which indicates that they really are targetting particularly dangerous mutants. The rescue mostly works, but Dani gets caught in the power-removing machine, leading them to think she's lost her powers (like they'd do that!) But that's not what happened: it's triggered what Grant Morrison will later call her secondary mutation (the third to be artificially triggered in an X-man, I think, after Lorna's magnetic powers in X-Men #50 and Hank's change of appearance in Amazing Adventures #11). Her mirages are now "real", and start eating everyone. Fortunately, she can only have one outstanding mirage at a time, so is able to cancel the angry multi-toothed red monsters by calling up a spear instead.
At which point the Hellfire Club turn up. The Mutants put the goons into Limbo, and sneak back to Westchester, leaving Amara back in Nova Roma. Magneto arrives there eventually, explains what happened (yeah, had to save Amara, she just got teleported away mysteriously to Nova Roma when we were about to reach her, how weird), and presumably Illyana looks guilty as hell. But he says no more? He knows he has nothing to teach them, and can't control them... What is the point.