Primus (Dungeons & Dragons)

Primus is the supreme ruler of modrons, in the Dungeons & Dragons roleplaying game.

Publication history
Primus (The One and The Prime) first appeared with the modrons in the original Monster Manual II (1983).

Primus appeared in the Planescape Campaign Setting boxed set (1994). In the adventure The Great Modron March (1997), the modrons are set on an unusual course, and in the adventure Dead Gods (1997), it is revealed that the Primus who sent the modrons on their march had been killed and replaced by a being with a mighty power.

Primus appeared with the modrons in the web enhancement for the third edition Manual of the Planes in 2001.

Description
Primus manifests as a gargantuan humanoid rising from a pool of pure energy, or as an androgynous human. In its gigantic form, its right hand is obscured by rainbows (a portal to Arcadia) and its left hand by darkness (a portal to Acheron).

Primus is aware of all modrons, because it is at the top of the hierarchy.

In 4th edition, the modrons are described as "cells" of the unknown being Primus.

Relationships
Primus is the supreme ruler of all modrons. The four secundus modrons report directly to Primus.

One Primus was killed by Tenebrous, the undead shade of the demon lord Orcus, using the Last Word, an utterance so powerful that it can destroy deities.

Chourst once visited Mechanus, although he barely survived the encounter; Primus itself showed up to deal with the slaad lord after he had worked enough mayhem and disorder on the orderly plane, and still seeks justice against Chourst.

Realm
Primus resides on the plane of Mechanus, in Regulus, the home of the modrons.

History
The history of Primus, like the history of the modrons, is possibly as old as the planes themselves. It may be that the modrons shaped the gears of Mechanus in the Age before Ages, or that the gears of Mechanus shaped the modrons from the stuff of pure Law. It's suggested that the first modrons might have been proto-inevitables who learned to store energy in a central pool of energy, or that they were creatures of pure geometry that the plane of Mechanus slowly transformed into constructs. 4th edition suggests that Primus may have been a machine-like primordial.

For eons Primus existed at the hub of the central cog of Regulus, the supreme intelligence of the modron race. If by some calamity Primus was destroyed, a secundus modron was immediately promoted to replace it. However, in this time of transition, while the new Primus examined the state of the planes and its race, some chaos would enter the modron species, something that other races sometimes mistook for civil war.

For as long as records have been kept, Primus would call forth a Great Modron March every seventeen cycles of Regulus's largest gear (each cycle lasting 17 years by Oerth's reckoning). During the Great Modron March, "thousand upon thousands" of modrons would transverse every outer plane in the Great Wheel, trampling those who got in its way, with those few who survived the journey reporting to Primus on what they had witnessed. Some believe the March has no purpose other than to temporarily bring a modron's vision of order to every plane, while others believed the purpose was simply to destroy as many modrons as possible and thereby renew the modron race.

In approximately 587 CY, however, an unprecedented disaster occurred: Primus was slain by the undead shade of a demon god, who secretly replaced Primus in the Infinity Web of the modrons, guiding the entire modron race without the knowledge of anyone else. Impersonating Primus, Tenebrous called for an early Modron March, disrupting the cycle that had previously been as regular as Mechanus's own clockwork gears. At Tenebrous's direction, the modrons scoured the planes for the long-lost Wand of Orcus, which Tenebrous needed to complete his resurrection and prevent the slow death he was experiencing as the possessor of the Last Word. When this Rogue March was completed, Tenebrous simply abandoned the modrons, leaving them to promote a new Primus in his place. The version of Primus that the Last Word had destroyed now exists as a vestige.

However, Tenebrous's fell taint had corrupted the modrons, and one of the secundi contested the promotion of one of its fellows. While normally promotion was instant and the egoless modrons accepted the arbitrary elevation of one of the four secundi as the proper order of things, Tenebrous's lingering influence inspired one to invoke an ancient rule that permitted Primus's successor to be chosen through a contest. The terms were simple: whichever secundus destroyed the most chaotic beings in a single week would win. While one traveled to Limbo to single-handedly massacre slaadi and similar creatures, the tainted secundus instead ordered its subordinates to destroy towns of gnome petitioners on the plane of Bytopia. At the end of the week, both secundi declared victory, with the one who had gone to Limbo objecting that the souls of Bytopia were not purely chaotic; nor should acting through subordinates have counted. The tainted one disagreed, and instead of accepting defeat it led nearly a million subordinate modrons on an exodus of the plane, bringing them to Acheron and promising to build its military might so that it could take Regulus by force. Though the promotion of the other secundus went on, the modron race had been divided, even crippled.

The formians took advantage of the modrons' weakness, invading Regulus and taking control of outlying gears formerly under modron control. Thus far, however, the energy pool of the modrons has spawned new modrons for every one destroyed, resulting in a stalemate. The inevitables, too, expanded into modron territory in order to gain new resources for their kind, though recently (as of 597 CY) the new Primus has formed a truce with the inevitables, granting them space in Regulus and monodrone assistants in the inevitable factories in exchange for the ending of hostilities.