Metadeus (3.5e Elder Evil)

Background
Free will is one of the greatest of boons to sentient beings, yet not all things are within their grasp to change. In opposition to free will lies destiny, the pre-determined fate of all beings. Summary::It is the sentient manifestation of fate, the desire for the universe to follow a certain course of action. The stories of time travel where the past refuses to change, the inescapable fate, such is the work of Metadeus.  It is uncertain if Metadeus is the inevitable result of the existence of destiny, or of it is a construct created by some long-forgotten overdeity demanding the flow of time remain in its due course, but Metadeus now has but one purpose: to ensure events that must happen, do, and sometimes what must happen will only spell doom for us all...

Goals
Metadeus is focused on maintaining the course of destiny by any means. Unlike most Elder Evils, Metadeus has a deep interest in the affairs of mankind, and makes subtle adjustments to ensure what must be comes to pass. Metadeus attempts to keep his presence subtle, until destiny is grossly violated. When such happens, Metadeus draws near the material plane, beginning the assimilation and suppression of aberrant elements until the course of destiny can be once again brought right, no matter the cost.

Metadeus in the Campaign
Metadeus might first appear as a subtle presence, a mad cultist or a man influenced by an unknown presence from beyond the stars. Its name and corruption is barely felt, but incredibly precise to ensure the right actions happen at the right time in the right place. His presence isn't always baneful as well. If destiny demands that a certain man lives, agents of Metadeus will ensure that he is saved from the burning building as a child where he otherwise would have died. However, Metadeus often appears when a terrible event that must occur does not, often thanks to the free willed influence of heroes saving the day. In an attempt to correct what has gone wrong, Metadeus will appear and ensure the horror that was just stopped shall come to pass.

Description
Metadeus is difficult to describe, for Metadeus is in truth a hive mind. All of those physically corrupted by Metadeus are, for all purposes, Metadeus as well and will define themselves as such. With that said Metadeus does possess hubs of consciousness in two stages, the "queens" of the local hivemind, to which Metadeus can manifest directly through, as well as the actual physical body of Metadeus which lies somewhere lost on the Temporal Plane, deep within its shifting gray sands of time. Rarely seen, this body is said to be a titanic mechanical structure of black iron, glowing green energy, and impossible geometries. Seen with anything from 4 to 20 sides, Metadeus is as large as a moon and seemingly artificial. It is said that within the confines of Metadeus's body lies the answer to all questions, both asked and yet to be asked, as well as the knowledge of the fate of the entire world. Any who has gone as far to check it though has never returned, slain or driven impossibly mad. It is uncertain but it is said Metadeus has some vague connection to the metacube artifact in Sigil, whose ever-changing surface mathematically describes the conditions of all creation.

Sign
Sign::Assimilation

When things do not go as planned, there is only one reason; free will. Free will's chaotic influence has ultimately disrupted the flow of things, and as a being of absolute law, Metadeus cannot allow it to continue while repairs are being done to the flow of time. Mechanical creatures and lawful inevitables and modrons feel the influence first, becoming the shock troopers to Metadeus' growing presence. Then the corruption grows, infecting organic creatures with pseudo-technological pieces and removing their free will, adding their knowledge to the hivemind and replacing their desires with Metadeus. If left unchecked, all the world will become Metadeus, until the event that must occur does, or Metadeus is defeated and the means of Metadeus's influence is sealed off.

Faint: Lawful outsiders and constructs, specifically inevitables and modrons, begin to gain new orders on what their purpose is. This inevitably leads to a growing host of such creatures attempting to right what has gone wrong, and curiosity and confusion onto where the creatures have gotten their orders. For lawful outsiders and construct PCs, mental infection can occur on any lawful-aligned plane, where each week they must make a DC 15 Will save or fall under a geas/quest effect at caster level 20th.

Moderate: Affected creatures gain the assimilated template, and can spread this template to others in a ritual which takes 1 hour, no save. The subject must be rendered helpless for this to work, and after the transformation their body is scarred and marked with seemingly cybernetic parts. Unlike the template, constructs may be affected as well, although they get a Will save equal to the save against mental corruption. They have no free will and follow the will of Metadeus. The DC to avoid mental corruption rises to DC 20 and is required daily.

Strong: The assimilation process may now be employed on any creature which is dazed or stunned, and assimilated creatures become extremely difficult to defeat. Their fast healing rises to 5 and they adapt to attacks. When physically attacked, the assimilated creature and all assimilated allies in 60 feet gain a cumulative DR 2/-. When attacked with elemental damage they gain a cumulative energy resistance 5 against the appropriate element. Against effects that require saving throws, they gain +4 to their saving throws against the same spell or effect. The effects last for 24 hours, or until this group of assimilated is destroyed. It is important not to let other assimilated join the fray. New assimilated creatures will pick up the adaptions of the current group until there are no more left. Finally the mental corruption DC rises to 25 and applies to any non-chaotic outer plane.

Overwhelming: Assimilated creatures only need 1 minute to assimilate another being, and may perform assimilation against a grappled target. Their fast healing rises to 10 and Metadeus physically appears in the sky as if a small moon. The material plane falls victim to the mental corruption, which rises to DC 40 for lawful outsiders and constructs, but may also infect any other creature capable of being assimilated, with a DC 20 Will save. If such occurs, they are under the effect of geas to find assimilated creatures and submit for assimilation at once.

Malefic Properties
Anathematic Secrecy: Immune to all divine divination spells and effects.

Dark Visiting: The ever-present mental hum which suppresses free will is troubling and wears on the mind of those in range.