World B is the world of Dissidia Final Fantasy and its prequel Dissidia 012 Final Fantasy, though it is only named and shown in the latter. It is a near-mirror image of the world of the original Final Fantasy, which is called World A in Dissidia 012.
Dissidia Final Fantasy implied the world drew from the other Final Fantasy worlds. World B's nature is expanded upon in subsequent games; Dissidia 012 Final Fantasy reveals gateways were used to allow visitors into other worlds, and Dissidia Final Fantasy NT posits World B grows by feeding on the memories of summoned warriors.
Chaos, Cosmos, and Cid of the Lufaine arrived in World B from World A when Chaos opened a portal to the Interdimensional Rift that drew them in. Shinryu was visiting World B, one of the many dimensions connected to the Rift, and took an interest in them.
Cid made a pact with Shinryu to gain immortality in exchange for giving up his body. Chaos and Cosmos would war with each other using World B as the battleground, and call warriors from other worlds through the Rift to their side to fight for them. Cosmos made her throne in Order's Sanctuary on an island off the coast of Cornelia, while Chaos's throne lay inside a volcano on a floating island near Onrac.
In the twelfth cycle of war, Exdeath opens a portal to the Void near Onrac and releases the manikins the Onrac of World A had produced and sealed away. The manikins swarm World B, threatening to overwhelm Cosmos's forces with sheer numbers, until six warriors venture into the Land of Discord and sacrifice their lives to close the portal. In the thirteenth cycle the southern regions of the world are destroyed when Chaos kills Cosmos, but her warriors survive due to the light of their Crystals and make it to Chaos's throne and destroy him, ending the cycles of war and spiriting them home.
In a secret ending, once Cid is freed from the nightmare world depicted in Confessions of the Creator, he tells Cosmos—who has revived in World B and was waiting for him—that the world will collapse into the Rift now that the balance of power between her and Chaos is shattered. Cid offers Cosmos to join him on a journey, but she rejects the offer, choosing to stay and reign over the abandoned World B for as long as it has left.
As revealed in Dissidia Final Fantasy NT, World B resisted collapse after the appearance of Materia and Spiritus, two gods born from Cosmos's and Chaos's wills. The two gods summon champions from other worlds to sustain World B with battle energy whose memories expand the world. Shinryu, in an attempt to consume the world and its memories, threatens to bring World B back to the Void, but is vanquished by the gods and their champions. After the warriors depart back to their home worlds, projections based on their memories continue to be used by the gods for battle energy.
In Dissidia 012 Final Fantasy, with the exception of Confessions of the Creator, the player is restricted on which areas of World B can be explored depending on which storyline they are playing. Certain gateways may be inactive in one story, but active in another. Confessions of the Creator gives the player free reign to explore and features Teleport Stones to warp the player around the world.
Connection to World A
World B regions are named after World A's, and several gateways are directly named after its locations. Though the worlds are similar, there are several geographical differences. There is a circular island in World B off the coast of where Cornelia is in World A—this island houses Order's Sanctuary.
The island chain between the two northern continents in World A is a continuous strip of land in World B, and the northwest continent in World B, the Lands of Discord, have a chain of floating islands on their eastern shores housing the Edge of Discord gateway where the Edge of Madness, the seat of Chaos, lies. Peninsulas on the eastern edge of the map and near Melmond are lengthened to provide land bridges, and there are numerous additional small islands, including the Shinryu Isles in the southeast, that contain a Teleport Stone to the Land of Discord.
- Cornelia Plains: The main region encompassing Cornelia and Pravoka, as well as the Southern Lufenia Gateway that acts as a blockade to the northern continents. Lies in the north-east of the southern landmasses.
- Melmond Fens: The region in which lies the Melmond swamplands and the Western Keep, also contains the Chasm in the Rotting Land and Curses and Hopes of Yore gateways on the landmass to the west near the Cavern of Earth. Lies in the west of the southern landmasses.
- Elven Snowfields: A region lying in a snowstorm surrounded by ice-capped mountains, contains the Shinryu Isles and Ryukahn Desert at its far eastern area, and the Marsh Cave in the west, which is the location of the Land of the Stolen Crown gateway. Lies in the south of the southern landmasses.
- Ancient Volcano Ring - Gulg: Centering around Mount Gulg, includes the eastern outlying areas around Crescent Lake. Lies in the east of the southern landmasses.
- Mirage Sandsea: Centered around the Yahnikurm Desert and Mirage Tower, also encompasses Lufenia and Gaia, and contains the Dreams of a Flying Castle and The Forsaken Lands gateways. Lies in the north-east area of the map.
- Bahamut Isles: A strip of land corresponding to the Cardia Islands chain in World A, contains the Citadel of Trials along with The Dragon King's Gateway. Lies in the center northern area of the map.
- Land of Discord: Consisting of Onrac and the desert regions to the west, also contains a chain of floating islands on the east coast. Lies in the north-west part of the map.
World B appears as a background in a Field Music Sequence.
- In the Report titled "One Man's Monologue", Garland notes he mistakenly believed World B to be World A 2000 years in the past. This refers to the original Final Fantasy's time loop. The destroyed condition of the world implies there was a major catastrophe in World A's past, which coincides with statements made in the later Reports about a war and a cataclysm caused by Chaos occurring around this time.
- In spite of Cid's statement that escaping from World B costs an enormous amount of energy, he sent the Warriors of Cosmos back to World A using a Teleport Stone after Chaos's destruction. It is not explained how the Warriors are summoned in the first place.