The Clockwork Nirvana of Mechanus is the lawfully aligned outer plane of cogs, gears, and order.
Modrons are the sole natives of Mechanus, though other lawfully aligned creatures have also come to inhabit the farther reaches of Mechanus' great cogs.
About
The predictable and orderly nature of Mechanus and its Modron inhabitants meant that all chaos or unpredictability was thrown out the window long ago. There is never a chance something might occur. It either does occur or it does not, and usually due to the predictable nature of the plane, it can be determined ahead of time whether or not a course of action may succeed.
History
Mechanus wasn't born or created, instead it was solved. When the gods started to shape the primordial void in the beginning of days, their work brought the concept of order into the realm. As a consequence, a being of pure though embodying this ideal was born, the Formula of Law. Around the Formula of Law was formed Mechanus, a perfect shifting pattern of shapes and elements in perfect harmony.
Eventually, this realm and the Formula of Law was discovered by a being who would become known as the Architect. The Architect was fascinated by what the Formula of Law was creating. The Architect built a body for the Formula made of pure energy and christened it Primus. Over time the Architect was joined by other like minded creatures who strived to create order, and they became the first tribunal of Axioms, dictating the laws for Mechanus and the planes beyond.
But the peace of Mechanus would not lats forever, as its creation drew the attention of a being from beyond the void, an eldritch monstrosity and world eater, the Nine-Fingered Worm. Drawn by Mechanus' light he Nine-Fingered Worm sought to devour Mechanus and bring chaos to its order. Primus and the Nine-Fingered Worm did battle, and in the end Primus was able to defeat the eldritch evil by cutting of its tail, hurling it into the void, and banishing the Nine-Fingered Worm to the edge of reality. In the void the worm's tail would form into the realm known as Limbo and from its flesh would be born the Slaad. Throughout the fight, Primus would not go without being wounded himself, and his blood would form into a race of mortals known as the Modraheed.
But the battle between Primus and the Nine-Fingered Worm planted a seed in the mind of the Tribunal of Axioms that would change the fate of Mechanus forever. Seeing the chaos wrought by the battle and the wounds sustained by Primus, they saw how weak and inefficient the flesh was. Over the next millennia the Tribunal would slowly replace their bodies with cold and calculating metal and machines until there was nothing of their mortal forms left. Then, when they were done improving their own bodies, they moved onto improving the bodies of the Modraheed, turning them from a race of humanoids into a race of constructs, from being the Modraheed, to being the Modrons.
Notable Locations
Regulus
Regulus is the largest and most famous city in Mechanus, built atop the central cog. it is the home of the Modron as well as the seat of primus and the Tribunal of Axioms. Here the law of Mechanus are the strictest and all actions most ordered. It consists of countless perfectly measured cubes and gears interlocked in mathematical precision.
The Labyrinth of Numbers
The Labyrinth of Numbers is a massive shifting maze and calculator used to continuously solve the Formula of Law. Only Modrons of high enough clearance are allowed to enter and one cannot exit the Labyrinths twisting corridors without calculating the Formula of Law for themselves.
The Tower of Thought
The Tower of Thought is a massive foundry at the center of the Labyrinth of Numbers and is the home of the Inevitables, massive constructs that enforce the universal laws across the realms. Inside the Inevitables are crafted and held until they are deployed by the Conundrum Engine, a massive glowing sphere that scans the realms for those that violate the laws of the universe before issuing a Writ of Order and sending out an Inevitable return toe realm to order.
Quartz Cove
Quartz Cove is a notable 'port town' in Mechanus, meaning that it has a tightly regulated portal of entry to and from the Infinite Staircase. Quartz Cove is also home to a tavern known as "The Loose Screw", run by a small but dedicated team of Warforged. In addition, Quartz Cove also contains a high security prison, used to contain and entrap dangerous individuals before either sacrificing them to Primus or sending them back through the portal.
