yeah, she came close twice. well........kinda 3 times.
1)he was sleeping and she had a knife. she told herself she wouldn't kill, and he woke up when she put the knife down. yeah, I know they didn't fight in this one, but still......she could have killed him.
2)she almost knocked him unconsious by causing a blizzard. she didn't know cold made him stronger though. she thought he was dying so she stopped the attack. he was close to unconsiouness
3)she suffocated him by switching the air pressure. he threw colossus at her though and her attantion was divided. she evaded colossus(i think, he may have hit her) and she continued the attack. he then took control of the lightning, tripled it's power, and sent it through her whole body. she was fighting the ligthning, while still suffocating magneto, and she finally gave up.