Well, for one, Zatanna tends to be out early in the mornings...so she'll almost certainly catch sight of the giant fireball streaking through the sky. I would also not be adverse to her treehouse sustaining considerable damage...though, as there are at least two others who (sometimes) live there also, I'm not sure how that would work out.

(Li? Ellie? What do you two think?)

I also like the possession idea. Considering past talks she's had with people over the idea, I think there could be a lot of potential development and/or drama resulting from something like that happening.