Magic the Gathering Worlds - Planes
A plane is a self-contained world or universe of any size found within the Multiverse of Magic: The Gathering. While planes can be governed by any conceivable set of rules and natural laws, or indeed even inconceivable ones, most planes visited in the storyline are comfortably similar to Earth.
Most planes are spheres with an atmosphere and one or more suns and moons; they resemble planets. But there is no law of physics common to all planes of the Multiverse. Planes can be infinite expanses of matter, tiny specks of empty space, or logic-defying inversions of normal reality. A plane can contain an entire, sprawling universe or nothing at all.
Information taken from: https://www.mtg-multiverse.com/Â