In the cosmology of Eberron, thirteen planes orbit the Material Plane, each representing a fundamental aspect of existence—life, death, war, dreams, and so on. Yet, ancient texts and prophetic fragments speak of a fourteenth plane, a realm that once existed but is now lost, hidden, or forgotten. This plane is unnamed in most canonical sources, though some scholars refer to it as Mechanus, borrowing terminology from other cosmologies, or more poetically as the Plane of Time, the Clockwork Realm, or the Axis of Order.
Unlike the vivid and active planes like Fernia or Thelanis, the Unknown Plane is defined by absence, mystery, and speculation. It is said to have once governed the flow of time, the structure of causality, and the balance of cosmic law. Its disappearance—or deliberate removal—has left a metaphysical scar on the multiverse, and its absence is felt in the unpredictability of fate, the fragility of prophecy, and the chaos of mortal will.
Some believe the Unknown Plane was sealed away during the Age of Demons, when the progenitor dragons shaped the world and the Draconic Prophecy was first inscribed. Others claim it was consumed by Xoriat, its logic devoured by madness. A few radical theorists suggest that the plane never existed at all—that it is a conceptual placeholder, a symbol of what cannot be known or controlled.
In rare texts, the plane is described as a realm of perfect symmetry, where time flows in crystalline patterns and every action has a precise and predictable consequence. Its terrain, if it ever existed, may have resembled a vast clockwork mechanism, with gears the size of continents and rivers of flowing time. Beings native to this plane—if any remain—would be entities of pure order, perhaps akin to inevitables or modrons in other cosmologies, tasked with maintaining the integrity of causality and resisting the entropy of chaos.
The Draconic Prophecy hints at the Unknown Plane in cryptic verses: references to “the lost gear,” “the silence between seconds,” or “the eye that watches but does not blink.” These fragments suggest that the plane may still exert influence, subtly guiding events or preserving hidden truths. Some believe that certain dragonmarks, especially aberrant or artificial ones, may be tied to the remnants of this plane—echoes of a system that once governed destiny with precision.
In terms of magic and metaphysics, the Unknown Plane is often associated with chronomancy, divination, and lawful constructs. Spells that manipulate time, enforce contracts, or preserve order may draw on its forgotten essence. Some rare artifacts—such as time-stopping devices, prophecy-bound relics, or planar compasses—are said to resonate with the plane’s lost frequency, allowing glimpses into its structure or even temporary access to its power.