Even assuming Lelouch's power would work on a vampire, and that he even has a chance to finish his sentence before Eva hits him, what command would he give? He doesn't know she's a vampire, what her weaknesses are or anything. He could say 'kill yourself', which would be a meaningless command, as Eva isn't alive in the normal sense of the word. He could say 'hold still and let me hit you', which would be similarly ineffective due to Eva's incredible durability and regeneration.
He only will get one shot at it before Eva realizes what his power is and smashes in his larynx.
Evangeline wins this easily.
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~~~~Yay~~~~