The breath wooshes out of Cass, but she can fight for ten or twenty seconds without breathing. She slips into position and locks an arm across X's throat. Five or ten seconds should be enough to render even X unconscious.

Of course that won't last more than a few seconds, but it's all Cass can hope for.

She doesn't even wince when X finds the nerve cluster. They've both had interestng childhoods, after all.