[Katara relaxes a little, growing more comfortable and interested at Hermione's explanation of what she and her friends were doing.]

Yeah, just like that. And could do a few basic moves, but I'm leaving for the draft tomorrow and I still have to practice tonight, so it won't be too impressive.

[Not to mention that she's spent the morning doing an intensive and frightening healing session.]

As for how it works... well, it's something that you have to be born with the ability to do, and it's something that you have to learn.