but several other 2nd edition products say there is only one Prime Material Plane rather than several. Introduced in the Spelljammer setting, the Phlogiston is a part of the Material plane. It is a highly flammable gaseous medium in which crystal spheres holding various Prime Material solar systems float, traversable by Spelljammer ships. The Feywild and the Shadowfell, the Parallel Planes introduced in the 4th Edition World Axis model, were incorporated into the 5th Edition version of the Great Wheel model. In 2015, D&D Creative Director Chris Perkins stated that 4th Edition sourcebooks on these planes were the best source of information for the 5th Edition. The adventure module The Wild Beyond the Witchlight (2021) is the first in-depth 5th Edition exploration of the Feywild and builds on the description included in the 5th Edition Dungeon Master's Guide (2014). Outer Planes Alignment-based planes. The home of gods, dead souls, and raw philosophy and belief. Transitive planes The transitive planes connect the other planes and generally contain little, if any, solid matter or native life. Astral Plane The Astral Plane is the plane of thought, memory, and psychic energy; it is where gods go when they die or are forgotten (or, most likely, both). It is a barren place with only rare bits of solid matter. The Astral Plane is unique in that it is infinitesimal instead of infinite; there is no space or time here, though both catch up with beings when they leave. The souls of the newly dead from the Prime Material Plane pass through here on their way to the afterlife or Outer Planes. The most common feature of the Astral Plane is the silver cords of travelers using an astral projection spell. These cords are the lifelines that keep travelers of the plane from becoming lost, stretching all the way back to the traveler's point of origin. A god-isle is the immense petrified remains of a dead god that float on the Astral Plane, where githyanki and others often mine them for minerals and build communities on their stony surfaces. Tu'narath, the capital city of the githyanki, is built on the petrified corpse of a dead god known only as "The One in the Void". God-isles often have unusual effects on those nearby, including causing strange dreams of things that happened to the god when it was alive. God-isles are also the only locations on the