A plane is a world that lies within the Ethereal Plane, as opposed to a planet, which exists in the Material Plane. Planes are generally artificial creations, most of which are remnants of Vel'kira. Unlike in the open Ethereal, a plane has its own dreamworld beneath it, and otherwise behaves similarly to a planet. Magic tends to be easier to use on a plane, but this isn't necessarily the case. Since they are within the Ethereal Plane, it is more likely for each plane to have its own unique rules and parameters of what abilities are possible and how well certain abilities work. While the main planes the Elkandu visit, the ones connected to Torn Elkandu, tend to have similar rules to baseline, some places may have wildly different ones for how magic works, or even be completely mana-dead.