Ah, yes. It's a lot like Bending - they physically manipulate matter, but they don't need any kind of motion to do it; they just concentrate, and it happens. This power isn't infinite, though; use too much or reach too far, and you can burn yourself out or become infused with elemental energy and die (burst into flames, evaporate into air, turn to stone, etc.). The power itself emanates from one of four nodes scattered about the world. There's more, but that's the basics of it.