Wonder Man
Can Medusa's psionic hair cuff Magneto and leave him as helpless as the greatest prison anyone could come up with.
I mean if she locks him to something and he kills her she could do it stronger than even Spider-man's webbing and it could be permanent.
https://tse4.mm.bing.net/th?id=OIP.UM3xTa3qmFehGN8i7JYzEAHaKL&pid=15.1&P=0&w=300&h=300
vs.
https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/MagnetoYardin.png/250px-MagnetoYardin.png
I mean if she locks him to something and he kills her she could do it stronger than even Spider-man's webbing and it could be permanent.
https://tse4.mm.bing.net/th?id=OIP.UM3xTa3qmFehGN8i7JYzEAHaKL&pid=15.1&P=0&w=300&h=300
vs.
https://upload.wikimedia.org/wikipedia/en/thumb/4/4a/MagnetoYardin.png/250px-MagnetoYardin.png