Limbo is the endless void that lies outside the Multiverse. It is a dark place of eternal cold and timeless undeath.
The threat of being swallowed into Limbo is one of the most feared things in the Multiverse. Losing the Game of Time can land one's soul in Limbo. The war between Law and Chaos is a serious threat to the stability of the Multiverse, and will, if not checked by the Jugadores and the Eternal Champion, plunge all of reality and all consciousness into Limbo forever.
The Fhoi Myore are sometimes called the Gods of Limbo, and are theorized to be the entropy-consumed corpses of Chaos Lords consigned to Limbo.