Especially when I have three scenes that I already want to work a certain way. (What's the fun in changing them to a dull description of her powers?) AND I need to limit her powers so she doesn't turn into a steamroller. . . .
Inverse square law, I think. Her effects drop off hard with distance. Inverse-cube law if I really need to dial her down. As long as there isn't physical contact between her and the person -- or a daisy chain of physical contact.
Except that she affected a bunch of far-off people. . . hmm. . . but that was over time. So there's going to have to be a clause that until she breaks it, the effect accumulates. She has to break off. That'll keep her on her toes.