The Threshold is an interdimensional region in Final Fantasy XI. It is the realm that lies beyond the Cavernous Maws and through which adventurers may travel between present-day Vana'diel and the Crystal War twenty years earlier. Atomos rules this domain, devouring unnecessary futures and depositing their memories in its infinite void.
A Cavernous Maw is a monstrous structure, much resembling Atomos itself, that is capable of drawing people into the Threshold and delivering them to another place or time. Maws are first encountered in the areas immediately adjacent to the Grand Duchy of Jeuno. These versions of the phenomenon have a lifeless, stony exterior. After being swallowed and delivered to the era of the Crystal War, adventurers encounter leathery, wriggling maws instead. These may be activated to return a person to the future and enable subsequent journeys through time by means of their petrified counterparts.
Another variety of animated Cavernous Maw appears in post-war Vana'diel as a connection to the alternate reality of Abyssea. Unlike their frozen kin, these Maws function without having first been visited from the other side.
A Veridical Conflux, literally a convergence of realities, is a dark crystalline structure also related to the Threshold. It is a gateway between distant places that cannot be seen by ordinary people. Those that experience the pull of the Cavernous Maws seem to have no difficulty spotting one. Such a conflux in wartime Xarcabard allows direct access to the Walk of Echoes within the Threshold. Atomos creates another in Grauberg in response to the designs of Cait Sith.
Still more confluxes exist inside the Walk of Echoes and the various regions of Abyssea. These function as transporters within a given area. Generally a cost is associated with their use, however.
Walk of Echoes
The Walk of Echoes is a series of stairways and landings floating through the Threshold. From these footholds travelers caught between Cavernous Maws can marvel at the gaping, fanged mouth of Atomos in the starless sky. Failing to find solid ground on which to stand, a visitor may instead tumble through the void and slip into another world.
With the assistance of Kupofried, a legendary Moogle, adventurers may journey to the Walk by means of the Veridical Conflux in Xarcabard. Once here, further confluxes lead to a range of special battlefields. In each a force of up to thirty-six people, who may arrive independently, face a group of monsters under a time limit. If the creatures are overcome, the participants are rewarded relative to their individual performances. Additional encounters become available as previous challenges are completed. Participation requires the expenditure of an item received from Kupofried, however, and opportunities are therefore limited.