Shadowlight Covenant

Shadowlight Covenant is often seen as polar opposite to the Immutable Hierarchy, its sworn archenemy. It’s only partially true. While the Hierarchy espouses tyranny of authority and societal hierarchy, the Shadowlight Covenant spreads the tyranny born of anarchy and everlasting competitiveness. Being a twisted form of meritocracy to the Hierarchy's twisted form of feudalism.
Shadowlight Covenant sees all moral norms and what is considered to be ‘laws’ of a civilized society as a form of tyranny, from which one has to seek liberation. They seek societal upheaval and ruin of all that they consider to be ‘chains’. They would probably rebel against the laws of nature too, if that was possible - there are the manifestation of the concept of refusing to bend to the rule of law, regardless of what the law is.
For members of the Covenant, might makes right and the strong naturally end up ruling the weak - but they will remain on the top only until someone even stronger arises from the masses to topple them. The ‘Revolving Door Revolution’ is a natural state for every society following the Covenant, an inherently self-destructive policy that is one of its biggest weakness - but also its great strength, as one can expect every leader of the Covenant to be incredibly cunning and powerful, always in their peak state (as anything less will inevitably lead to being toppled).
Gods of the Covenant - especially Luna - are inherently untrustworthy, gladly helping one to rise to power, only to immediately begin helping their enemies in toppling them. This doesn’t seem to be an issue for the worshippers of the Covenant, as said gods adapted the ‘follow my ideology not me’ approach. They, too, rebel against the authority - and are completely willing to let mortals do the same against the authority, although they will gladly accept any help that comes from the internal, free decision of said mortals (and will reward that with power).
As a result, they have become gods for the local subscribers of the Nietzschean-style outlook on the world. They offer power, but do not require (and in fact, dislike) the mortals grovelling in front of them. They are still playing their own game (and wage wars, in the Lost Lands and Spiritual Worlds alike), but the participation of their worshippers will tend to be seen as repayment for the boons they received.
In its own twisted outlook on the world, the Covenant seeks to ‘liberate’ mortals. Unfortunately, the results tend to be pretty horrible. Which doesn’t stop the Covenant from continuing its work.

Structure

Organization structures of the Shadowlight Covenant are loose. Extremely loose, in fact. Every operation of the Covenant, every society of the Covenant are a combination of ambitious individuals (doesn't matter if they are mortals, spirits or gods) who cooperate in some common goal, with every single one of them getting something out of that. The structures themselves arise and collapse almost at will.
Once again, this is both the Covenant's weakness and strength. Sure, a successful elimination of a leader can and will throw any Covenant force - even one on the verge of victory - into a disarray. However in many cases it will only turn out that you just eliminated a single member of a shadowy council that was chosen to lead that particular force, meaning that you will instead buy a few hours or minutes before the replacement appears (and you just played into their plan of eliminating the visible leader to take their place). What's more, even if you DID eliminate the sole leader of the army/plot, his underlings (save for some who were in for money) are probably a willing followers of said leaders' goal, and might simply - to avoid chaos - pick all the notable members of said army/plot and turned into a shadowy coterie of equals, and then push for the fulfillment of their goal before turning against each other over the spoils.
Because of that, while decapitation strikes against Covenants often do work, they also often do not work, sometimes completely against all predictions. The entire 'structures' of Covenants are always highly elusive and often way more flexible than anyone expects, and their (once again 'often') completely voluntary nature makes them capable of sustaining massive casualties without breaking apart completely. However, the organization (or army) you are facing can as well be under some highly contested 'revolutionary comittee' that will break at first occasion and only maintains their cohesiveness by terror. In the end, the chief trait of all forces of the Covenant is that they are utterly unpredictable and have to be thoroughly analyzed individually before a counterstrategy is devised.
Luna and other high gods of the Covenant tend to be held in a high regard by their theoretical followers, however in practise it's a much looser connection than even the one between the imperials and their gods. There is a plan of theirs in ther works, however one that is completely beyond understanding of every creature that isn't omniscient. It is played with sudden bursts of power given to random servants, the unexpected (and overwhelming) need to do some particular thing (sometimes completely nonsensical - but later on turning out to be a plan of some greater strategy) and sometimes through one of the gods of the Covenant appearing in ones' dreams and directly offering some supernatural boons for a certain action. There are even cases when Luna themself does that. But even then, there is always an option to refuse - and it's always part of the Covenant's great plan.

Culture

The forces and followers of the Shadowlight Covenant are almost uniformly backstabbing overthinkers - they tend to be very intelligent, cunning and will attempt to gather every piece of knowledge they can (after all, knowledge is power) and will do the same with combat skills and magic abilities. However are likely to fall into, as it was said, 'overthinking' - they are often paranoid to the point where they will expect knives coming from any direction and will keep making counterplans to plans that they themselves created (but it has to be said that this also makes the more notable members of the Covenant crazily prepared against all potential threats and capable of responding with overwhelming power and long-term plans to every attack or trouble).

Public Agenda

The Shadowlight Covenant has a goal, and an agenda. But only gods themselves might actually understand what it is. Total anarchy throughout the universe? Might Makes Right on multiversal scale? It's all pure speculations.

Territories

Domains

Lost Empires - When the Lost Lands were created, they swallowed many still-inhabited lands. Some of them remained inhabited to this day, resulting in many petty empires. Those that remained sane and loyal were eventually stabilized and became one more province of the Grand Empire - or were evacuated, if the stabilization was impossible.
Some of them, however, has Fallen. Resulting in their entire population becoming thralls to the Hierarchs. In the case of the Shadowlight Covenant it typically happened as instability and chaos took over, the supernatural support preventing them from fully collapsing despite the intense infighting. Sooner or later the truly powerful and cunning leaders emerged, maintaining their power through every mean possible (from personal loyalty to terror) and increasingly long periods of stability has began.
These countries are now in a state of perpetual chaos - and freedom. The governments serve as a framework for the eternal struggle for strength. There is no slavery - all are equally allowed to pursue power and shape their life however they want. Including by murder, torture and external imperialism. There is no stability, no help from the government (and often there is barely any government to speak of, at least until another shadowy coterie seizes power and makes their own laws that others can rebel against.
Evernight - A mysterious Spiritual World of eternal night, filled with shadow-covered forests and towers climbing towards the massive moon covering the majority of the night sky. Some say that there was a time when Luna herself resided in the now abandoned palace on the surface of the moon. Each of the towers is surrounded by a city, inhabited primarily by the Dead. Each city is independent, yet in a perpetual cycle of revolutions. Whatever revolutionary cabal manages to seize the control of the city can then use the magic gates on the top of it to send its troops to the moon, to wage a war for the control of the holy halls carved in it.
The war on the moon never ends. Eventually the ruler of the tower are toppled, but not slain - as the death doesn’t exist here, and to imprison someone forever and deny them a chance to grow stronger and fight is one of the actual sins in this realm. Once that happens, the overthrown ruler starts plotting - and eventually reclaims the throne. This cycle continues forever.
The Evernight is close enough (multiversally speaking) for the inhabitants of the Prime Material World to be often able to call down creatures from it (and occasionally visit it in person). This makes the Imperial Magic Guild and the Imperial Cult be at least vaguely aware of how does the Evernight look like and work like. Unfortunately, each question answered only opens a few more questions. The Evernight is a place where there is almost no information - only a lot of intentional misinformation, produced en masse by every of the perpetually changing coteries and powers.
Perpetual Contraption - An entire Spiritual World dedicated to science and understanding. Unfortunately, to the most horrible types of science and understanding. Nothing is sacred in these halls, and the concept of consent is a forgotten one. This is a place where mad scientists reign supreme, spending eternity constructing more and more insane things and testing them on subjects that have not agreed to anything.
It’s not hard to figure out what god is that place dedicated to. Laenimentus, Hierarch of Progress, is the chief deity of the Perpetual Contraption Every horrible invention of this place' inhabitants - from gas weapons to warped biological horrors - are dedicated to him, created through his teachings and used by his legions in their attempts to help the Shadowlight Covenant conquer the universe.
The realm itself is a world-size and planet-shaped collection of gears, with the cities themselves built atop slowly rotating and interconnected cogs. Each of the cog is an independent community, were - to maintain the proudest traditions of the Covenant - the smartest and most merciless of its inhabitants reigns supreme, forever on the lookout for emerging threats from those whom they rule.

Military

Shadowlurkers - Shadowlurkers are one of the most dreaded servants of Luna. It is said that they dwell in mysterious ruins deep inside the forests of Evernight, ruins that somehow appear darker than already pitch-black forests. Very few venture there and survive without their sanity and bodies irreversibly shattered (although since it's the Spiritual World, even the 'irreversible' things are pretty reversible, just on often ridiculous timescale).
Shadowlurkers are terror incarnate. Deformed humanoids of truly superhuman strength, dedicated to causing as much suffering and terror to their victims. They seem capable of disappearing and appearing at will when it’s dark enough, and they seem to be sucking the light out of their surroundings with their presence. They are living weapon of terror, capable of breaking morale of entire armies with their actions.
Nobody is sure what they are or how they came to be. They are occasionally summoned by Covenant’ cults, and are known from their penchant for changing the weak and unprepared summoners into still screaming collages of blood and flesh. Their strength, cunning and usefulness makes them remain popular despite all of that.
Shadows - Besides the shadowlurkers, the Evernight is also known for its shadows. They are alive, a chief reason why the light is so scarce in its cities. The smaller ones are merely usable as spies, but when they get larger... well, that's when the things get interesting.
Humanoid ones are incredibly agile and deadly combatants (although it depends on the presence of light - they die in perfect darkness and perfect light, but if there is a strong light source in general darkness, they get a lot more ‘sharp’ and well-defined, making them capable of causing even greater damage to anyone in the vicinity).
The largest ones (Luna’s equivalent of the titans) are nothing short of mass destruction weapons, capable of devouring entire villages in a matter of seconds and possessing some truly terrifying additional abilities. They are extremely dangerous, and require a very specific set of circumstances to be slain or even banished.
Clockwork Legions - The regular army of the Perpetual Contraption, occasionally called down to reinforce some insurgency or revolution backed by the Covenant. They are weirdly close to the real world ‘modern’ militaries in terms of organization and equipment, including some slightly weird form of rifles and numerous other techmaturgic gimmicks that can be very, very dangerous.
They are also utterly amoral, deploy numerous terrifying biological weapons (some of them used to be mortals), have a lot of ‘enhancements’ of various types, and occasionally bring heavy weaponry with them. In short, while shadowlurkers can scare enemies and shadows can assassinate them or kill them, Clockwork Legions are needed when you want to actually bring down an enemy fortress.

Religion

High Gods

The main god of the Covenant is naturally Luna, the Hierarch of Night, the rather elusive deity of anarchy, revolution, night and moon. The elusiveness comes all the way to their apparent gender (as the Luna appears alternately as a man or as a woman, and will answer any question concerning their actual preferred gender with claiming that their current one is what they truly are). And that's only the surface level of perpetual weirdnesses and lies surrounding Luna.
Luna is followed by two other high gods. First one is Laenimentus, the Hierarch of Progress, the divine mad scientist and a god of progress, change, technology and techmaturgy. The second one is Caedes, the Hierarch of Murder, a divine patron of the act of ending lives of the others outside of war and a legal system (and thus looks over both murderers and assasins).

The Fall

Ironically enough, the Covenant's love for free will goes as far as for it to require one's consent to be insidiously corrupted. The servants of the Covenant (even to the level of the gods) will gladly offer deals that have actually no fine print. They will sometimes try to screw you over, but it will be done in a rather mundane way. No corruption, no fates worse than death, just the equivalent of someone being used in the game of politics and then abandoned. However quite often (if not in a majority of cases) they will play straightforwardly with you.
The Covenant eschews ambition and strive for the top - and their very presence anywhere will result in others doing the same to counter their influence. How else can you stop the plots of a Covenant cult than by plotting against them? And how many of such counterplots will have their supportive organizations never disband, and instead look for something... more? Which, eventually, will lead them into the Covenant's hands - all, naturally, part of its grand plan.
At any point one can tie their live with the Covenant's goals. Aligning yourself - even temporarily - with any of the Covenant's operations, from the revolutionary movement against an oppression or an organization of murderers, will open you up for the Covenant's themed corruption for as long as you did that while knowing that they were part of the Covenant. Your motives do not matter - Luna accepts all of them. The same happens with those that ever struck a deal with servants of the Covenant mentioned above. After all, you agreed to be influenced by it, you wouldn't come willingly into contact with it if you didn't, yes?
The influence can be easily exorcised from yourself. You just need to consciously refuse it. But many fail to do that. Why would they? Who would abandon a world of ambitions, where you can actually raise to the top, where the more ambitious and powerful you are the more intelligent you become, and the more often you see the unexplainable coincidences (all contrived by your gods to help their grand plan that you are a part of) paving you the way to greatness?