Well Lily already knew what Tony yelled at her; that as combat goes she's a bit useless, in fact completely.

She hasn't had much practice with her voice except in her father's recording studio where she discovered she could enthrall any who heard her voice much as the Sirens do. She had ideas in the combat that she could see if the old adage "Music hath Charm to Soothe the Savage Beast" but like many here she isn't sure of her ability and plus suffers from the Teenage girl issue of not wanting to appear silly.

I was thinking about how song in the D&D Realm and other Fantasy RP can be used to inspire those in battle and add to their fighting power, calm their fears and even be used against an enemy but that may be a fantasy of it's own.