Exactly, it works best with fire though. Oh no, now you've made me put a price on it! I'm getting married next month. You have to come, and you have to dance with somebody. And take a box of my crystals and put them to use. Because I kinda filled up two for halloween alone.
The thing is, bad things can't get in. It's like a membrane. It would be useful if anyone's hurt, they could be dragged in to a circle, and I could shield the person doing the dragging, but I can't make them very big. Not unless I'm 'bursting' with a really strong emotion. And that runs the risk of me exploding a lot of stuff.