The Clockwork Nirvana of Concordium, sometimes shortened to Nirvana, is the plane of Lawful Neutrality among the Outer Planes.

Concordium is defined by order, regularity, and the principle that individual parts function within larger systems. Natural cycles follow reliable patterns, cause and effect are unusually consistent, and societies throughout the plane tend to place considerable value on responsibility, structure, and continuity.

The plane takes the form of a vast planar disk with two very different faces. Arcadia covers its upper surface as an ordered and fertile landscape, while Mechanus occupies the lower face as an immense system of interlocking gears and machinery.

Though sharply different in appearance, both express different aspects of the same underlying principle of order. The motion and structure of Mechanus contribute to the stability and regularity of Arcadia above, while the ordered living systems of Arcadia form part of the greater structure sustained below. The exact relationship between the two remains poorly understood, but neither face is believed to function entirely independently of the other.

Structure of Concordium

Arcadia and Mechanus are not separate planes.

Each occupies one face of Concordium and remains connected to the other through passages that cross the structure of the disk. These routes are usually dependable on the Arcadian side, while many Mechanus passages operate according to the movements and alignments of its machinery.

Neither face is known to possess an outer edge that can be reached by ordinary travel. Attempts to chart the full dimensions of Concordium have produced no reliable measurement.

Both regions are considerably more predictable than most Outer Planes. Change occurs, but it usually follows identifiable causes, established cycles, or the consequences of earlier events.

Order and Society

Cultures throughout Concordium tend to value reliability, obligation, and the role of individuals within a larger structure.

This does not produce a single form of government or society. Arcadian communities, formian hives, modron hierarchies, mortal settlements, and planar enclaves can differ substantially in their customs and values.

What these societies generally share is the belief that actions carry responsibilities and that functioning systems depend upon the relationships between their individual parts.

Concordium does not require those parts to be identical. Different people, communities, institutions, and even the two faces of the plane can serve very different purposes while contributing to a larger whole. Visitors are not expected to abandon their individuality, though deliberate disruption of systems upon which others depend is rarely tolerated.

Petitioners can be found throughout both Arcadia and Mechanus and commonly move between them. Over long periods, many develop subtle crystalline or metallic hues in the hair or skin, geometric patterns within the eyes, and shifting markings across the body. These patterns change with the individual and are sometimes said to become clearer as petitioners better understand their own choices, relationships, mistakes, and place within the systems around them.

The patterns of different petitioners can occasionally align when they draw close, forming larger designs that differ according to the individuals involved. Some petitioners eventually undergo a deeper transformation into crystalline planar beings known to scholars as axiomites. A solitary transformation produces a Navan, while several compatible individuals may voluntarily join through a process known as Convergence, becoming a more complex Aveneva. Axiomites are uncommon and possess no single hierarchy or common occupation.

Arcadia

Arcadia forms the upper face of Concordium.

It is an expansive landscape of plains, forests, orchards, rivers, hills, mountains, cultivated land, and carefully planned settlements. The countryside is fertile and unusually reliable, with weather and seasonal conditions following predictable patterns.

Rivers remain within established courses, crops grow with remarkable consistency, and settlements tend to develop according to deliberate plans rather than uncontrolled expansion.

Arcadia is ordered without being barren. Its forests, farms, gardens, and settlements are filled with life, though even wild growth often displays patterns uncommon on the Material Plane.

Forests and Orchards

Arcadian forests grow in broad, orderly stands.

Many trees possess bark with a metallic sheen resembling copper, iron, silver, or gold. Their leaves remain vivid throughout the year, and some species continually produce particular fruits rather than following ordinary seasonal cycles.

Certain fruits possess mild magical properties. Their effects vary between species and can include restoration, heightened alertness, temporary resilience, or other minor benefits.

Settlements cultivate many of these trees in orchards, though wild groves are widespread.

Wildlife

Arcadia supports animals resembling those found throughout the Material Plane, though many possess unusual coloration.

Foxes with golden fur, copper-colored rabbits, silver-woolled sheep, and similarly marked creatures are common. Many have pale or completely white eyes and display an unusual resistance to illusions and other forms of deceptive magic.

Most are peaceful unless threatened.

Ants, bees, wasps, and other creatures that naturally form highly organized colonies are particularly abundant.

The Orb of Day and Night

Arcadia's cycle of light and darkness is governed by the Orb of Day and Night.

The immense sphere rests high above the greatest known mountain range. One half radiates brilliant light while the other remains completely dark.

The Orb rotates at a constant rate.

As it turns, daylight and darkness move across Arcadia in exact succession. There is little natural twilight along the boundary, with one condition giving way rapidly to the other.

The cycle has shown no measurable variation in recorded history.

Settlements of Arcadia

Arcadian settlements range from farming communities and monasteries to extensive cities.

Roads are usually planned carefully, districts are clearly defined, and public works are maintained with an efficiency uncommon on the Material Plane.

Architecture varies between cultures, but geometric planning and long-term maintenance are widespread.

Arcadian societies often emphasize civic responsibility and cooperation more strongly than the rigid functional hierarchy found in Mechanus. Order here is commonly expressed through community, cultivation, stewardship, and dependable institutions.

Inhabitants of Arcadia

Arcadia is home to petitioners, planar settlers, formians, and a wide range of ordered creatures.

Formian colonies are particularly well established. Their hives are governed through strict social structures in which each member performs an assigned role.

Successful hives can become highly expansionist as they seek additional territory and resources. This frequently brings them into conflict with Arcadian communities whose own ideas of order leave greater room for individual autonomy.

Celestials from Celestia are also regular visitors, particularly along established planar routes. Devas, planetars, hollyphants, and other celestial beings may travel or maintain enclaves within Arcadia without being native to Concordium itself.

Portals of Arcadia

Arcadia possesses a limited number of permanent portals leading beyond Concordium.

The most important provide access to the Outlands, Celestia, and the Astral Plane. Other stable passages connect Arcadia directly to Mechanus.

Arcadian portals usually remain fixed and clearly marked. Many resemble elaborate gates, arches, or trellises constructed from pale stone, ivory-like material, or dark metal.

Their relative scarcity makes settlements surrounding major portals important centers of trade and travel.

Mechanus

Mechanus forms the lower face of Concordium.

It consists of an immense system of interlocking gears turning through an open expanse. Some cogs stretch for hundreds or thousands of miles, while others are small enough to function as individual platforms or components within larger mechanisms.

The gears intersect at different angles and rotate according to precise relationships with neighboring machinery.

No complete purpose for the mechanism has ever been established.

Some scholars believe its motion expresses the fundamental order of Concordium itself. Others argue that the machinery performs functions extending far beyond what planar travelers can perceive.

Gravity and Movement

Each major gear possesses its own gravity.

Creatures and structures are drawn toward either broad face of a cog, allowing settlements to exist on both sides.

Gravity weakens between gears, though the surrounding expanse contains breathable air. Creatures capable of flight can therefore travel between nearby mechanisms without requiring protection from vacuum.

Moving from one cog to another requires careful timing.

Gears may approach one another at unusual angles, and a safe route during one point in a rotation can become impassable later. Residents commonly measure journeys according to mechanical cycles rather than distance alone.

Light and Time

Mechanus follows a precise cycle of twelve hours of light followed by twelve hours of darkness.

No visible sun or moon produces this illumination. The surrounding expanse itself brightens and darkens according to an exact and repeating cycle.

Seasonal variation is unknown.

Settlements use this reliability to coordinate labor, transport, maintenance, and the operation of machinery across enormous distances.

Modrons

Modrons are among the principal native inhabitants of Mechanus.

Their society is organized into a strict hierarchy in which increasingly complex forms undertake increasingly complex responsibilities. Simple modrons perform repetitive labor, maintenance, transport, and guard duties, while higher forms oversee administration, communication, calculation, planning, and coordination across enormous portions of the plane.

Information moves upward through this hierarchy while instructions move downward.

There is no known sovereign at its summit.

Modrons describe their directives as the product of proper process, accumulated information, established law, and the requirements of the larger system. Outsiders have long debated whether the hierarchy ultimately responds to the machinery of Mechanus itself, to some hidden intelligence, or simply to processes too vast for an individual observer to follow.

The modrons appear largely uninterested in answering the question.

The Grand Array

The Grand Array is the largest known center of modron administration within Mechanus.

It spans numerous interconnected gears filled with archives, calculation halls, communication chambers, transfer stations, and mechanisms whose functions remain obscure to outsiders.

Modrons arrive constantly carrying reports and observations from distant parts of Mechanus. Others depart with new assignments, revised schedules, or instructions intended for regions far beyond the Array.

No central throne, ruling chamber, or singular authority has ever been identified.

Travelers permitted into its deeper regions instead encounter increasingly complex layers of administration, each connected to wider systems beyond it.

Whether the Grand Array possesses a true center is unknown.

Inevitables

Inevitables are powerful constructs associated with the enforcement of fundamental laws, bindings, and conditions.

They do not function as ordinary guards or officers of Concordium.

Certain mechanisms within Mechanus appear capable of identifying violations significant enough to trigger a response. When this occurs, an Inevitable may be activated, constructed, or assigned a directive appropriate to the violation.

Once committed to that task, it can pursue its purpose across extraordinary distances and over long periods.

Its concern is with the principle it was created to enforce rather than the laws of individual nations or settlements.

Exactly how Mechanus determines that intervention is necessary remains uncertain.

Other clockwork beings inhabit the plane as well, ranging from simple maintenance constructs to highly specialized entities whose functions are difficult for outsiders to understand.

Settlements of Mechanus

Large parts of Mechanus contain little native vegetation or wildlife.

The broad faces of many gears remain bare except for machinery, modron structures, or other constructed features.

Planar settlers have transformed some cogs extensively. Planned cities, enclosed gardens, farms, workshops, parks, reservoirs, and even artificial wilderness can all be found where communities have deliberately established them.

These environments depend upon continued maintenance rather than occurring naturally across the layer.

Buildings and infrastructure are designed around the motion and gravity of the gear supporting them.

Portals of Mechanus

Mechanus contains a large and carefully studied network of planar portals.

Most appear as pale or luminous circles whose borders resemble slowly turning gears. Many are situated near the centers of large cogs or within major mechanical structures.

Unlike the fixed portals common in Arcadia, Mechanus portals often operate according to scheduled alignments.

A passage may open once during each revolution of a particular gear, while another requires several distant mechanisms to align simultaneously.

Known destinations include the Outlands, the Astral Plane, other Outer Planes, distant regions of Mechanus, and Arcadia.

Rare artificial portals may lead elsewhere, but such routes are not part of Mechanus's ordinary natural network.

Travelers who rely upon these passages maintain detailed records of gear movements and portal schedules. Missing the correct alignment can leave a traveler waiting hours, days, or considerably longer.

Travel Between Arcadia and Mechanus

Arcadia and Mechanus are opposite faces of the same plane, but ordinary travel does not simply involve walking around the edge of the disk.

Stable passages connect the two.

Arcadian entrances tend to remain fixed and recognizable, often appearing as constructed gates, descending passages, geometric archways, or enclosed chambers.

Their Mechanus counterparts may emerge onto particular gears and can sometimes depend upon the position of surrounding machinery.

Some routes remain permanently available. Others become accessible only during predictable cycles.

Travelers familiar with Concordium usually treat movement between its two faces as part of the same journey rather than planar travel.

Connections to the Outer Planes

Concordium occupies the lawful position among the Outer Planes and maintains routes to the Outlands and neighboring Outer realms.

Celestia is most easily reached through established Arcadian routes, while passages toward Baator are more commonly encountered through Mechanus and other heavily regulated crossings.

These tendencies do not represent a moral division between the two faces. Arcadia is not inherently Good, nor is Mechanus inherently Evil.

They reflect differences in geography, historical travel, and the planar routes that have developed over time.

The Astral Plane remains the principal transitive route between Concordium and the Material Plane.

Natural Hazards

Concordium is generally hospitable to mortal life, particularly within Arcadia.

Most Arcadian dangers arise from political conflict, territorial disputes, expansionist formians, planar travelers, or interference with systems maintained by local communities.

Mechanus presents greater physical hazards.

Moving gears can separate travelers, close routes, or crush creatures caught between enormous mechanisms. Changes in local gravity can make transitions between gears dangerous, while missed portal cycles can leave travelers stranded far from their intended route.

Predictability does not make Concordium harmless. It simply means that many of its dangers can be anticipated by those willing to study the systems involved.

Survival

Arcadia provides abundant food, fresh water, breathable air, and generally moderate climates.

Mechanus also possesses breathable air and stable temperatures, though food and water are unreliable outside inhabited gears.

Preparation is particularly important when traveling through Mechanus. Accurate maps, portal schedules, knowledge of gear rotations, and sufficient mundane supplies can greatly reduce the risks of travel.

Visitors should also learn the customs of the societies they enter. Concordium accommodates many forms of ordered life, but those who deliberately disrupt systems upon which others depend can quickly find themselves unwelcome.