Welcome to the new Sinister Design forums!
It doesn't really work as offense. Luca just weakens the enemies. She demoralizes them. That's all.
Why does Luca know Mindblast? Why is she able to Soul Suck? Those too are offensive.
Yet people up her Psy power to up her psi points. Which effectively ups her attack.
Yep. Her physical resistance really helps.