Full write-up: https://www.cbr.com/x-men-polaris-an...ombine-powers/Polaris creates a barrier for them using her control of magnetism, and Jean's telepathy ends up affected as it goes through it -- amplifying it as it moved through Polaris' heavy magnetic field and allowing her to pick up the stray memories of the alien who sacrificed himself to unleash the horde in the first place. As Jean explains to Lorna, the alien's brain was swallowed whole by the swarm -- meaning its neurons are still firing. By locating the brain within the creature that ate it, Jean is able to make contact with the creature's mind. The Omega-Level telepath admits to Polaris she's never been able to touch a dead mind with her powers before. But Jean pushing her telepathy through Lorna's magnetism has effectively created an "MRI machine for memories."