The Supernal Lay is the official term for an "overlaying" realm, which is sometimes referred to as Dreamworld, Underrealm, or the Big Ether. It is a place only accessible my magic and sometimes with the help of psychedelic substances. It was believed that this was where lost ghosts, visions, nightmares, dreams, and memories existed simultaneously. Some creatures also resided there, such as the wraighs; because of this, they were capable of using it to travel near instantaneously, where they could be summoned back to the material plane.
Use in Magic
Those who practice the art of Perciperation, such as the I'dinar and some Eari and Draol, could visit the Supernal Lay to access memories and visions.