As Katara's eyes close, Roxie fumbles at her neck, pulling a small silver bell on a chain from around it. But as she holds up the bell, it smoothly changes, becoming the size of a dinner plate. And the fingers of her other hand trace alog the side of it--

A pure tone rings out, rippling into registers beyond human hearing, weird-edged enough to induce instant goosebumps and nearly make the bones of Katara's spine and ribcage vibrate.