Rapturous Ecstasy

Rapturous Ecstasy is the force of materialized and almost elemental hedonism and self-indulgence. Drugs, food, alcohol, sex, even art and music - everything that can be indulged in for pleasure will find its own share of love among the ranks of the Ecstasy (although the actual influence of that particular indulgence among the forces of the Ecstasy will typically vary depending on how popular and common is suicidal pursuit of it among the mortals)
In its search for pleasure, Rapturous Ecstasy is just as amoral (and actually against morals as a whole per rule) as the forces of the Immutable Hierarchy, and just as inherently societally self-destructive as the Shadowlight Covenant. It seeks liberation from all chains (typically including the moral ones) just as the Covenant, but sees no issues with establishing self-centered and abusive tyrannies like the Ecstasy, for as long as those at the top enjoy their place.
The Rapturous Ecstasy’s ranks are infinitely varied on the inside. Its hierarchies are fleeting and terrible powers can be found even among the meekest of its servants. It's an utterly unpredictable and moody force, always acting on a weirdest of whims. It’s its greatest weakness and most potent of strengths. They are just as unpredictable as the Covenant, although unlike the Shadowlight's common 'All Part of the Plan' situations, the Ecstasy can do something unpredictable for no other reason that their own mood.
Its gods reward the abandonment of all plans and goals save for self-indulgence - but at some point, the self-indulgence becomes both a plan and a goal. A lord of one of its earthly domains might organize a full-scale assault on some city merely out of desire for the body of its lord or his wife - but secretly, that whim actually furthers the long-term plans of the gods of the Ecstasy. Someone’s quest for a new drug will end with tens of thousands enslaved to it and corrupted to the will of the Ecstasy - and so on.
The legions of Ecstasy are often underestimated. Their popular image in the culture of the Grand Empire and other Fallen is that of an army of drug junkies and obese drunkards (not to mention the more sexual stereotype), too busy screwing around to be dangerous. And while it’s true for some of its worshippers and spirits (gods even), it’s far from being universally true. The blessings of Ecstasy often off-set the weaknesses born of self-indulgence. Drug-addict will find itself stronger and more resistant while under influence, and no longer addicted to any particular drug but instead to the very concept of drugs. Obesity will no longer cause health issues, and sex becomes a potent tool for seduction, manipulation and depravity.
Many worshippers of the Ecstasy, especially those experienced in their craft, are in fact supremely creative and intelligent individuals that are capable of doing all manners of horrible things to spread what they perceive as ultimate good to others, regardless of whether they liked it at first.

Territories

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, become thralls to the Hierarchs. In the case of the Rapturous Ecstasy it typically happened when out of despair the survivors turned towards hedonism, hoping to wait out until their own eventual demise. Soon daemons of Ecstasy walked the streets and instructed those around them how to find more and more pleasure, and things steadily progressed from there.
Today those countries are places of absolute freedom. Hedonism and the pursuit of pleasure are the greatest values. Bodies are altered, drugs are created and feasts are organized almost constantly. Great pieces of art are created too, although sometimes the creativity takes the better of the creators and results with things that most certainly cannot be shown anywhere in the civilized lands.
As one can imagine, this isn't a particularly constructive form of statebuilding, resulting in many of the lost empires of the Ecstasy tethering on the verge of abyss - and typically made to run (at least somewhat) by large slave population. One can expect those countries to be ready to buy any slave they can, precisely to support their own decadent culture.
Paradise Halls - The nearest Spiritual World controlled by the forces of Ecstasy, Paradise Halls is a place of endless indulgence. World-sized palace where all sins are indulged constantly, and all manners of organization have more in common with fetish-induced roleplaying than concepts of duty and authority.
Deep inside it lies the Inner Palace, where one of the numerous children of Procacitas rests on their throne, surrounded by a court and a praetorian guard that also double as a harem. It is a place of serenity and regal beauty, surrounded by the endless sea of constant depravity. Many wonder how long it will be before the master of the Inner Palace gets bored of this setting.
Despite appearing weak, the Halls have repelled (and often corrupted) numerous invasion forces in the past. They also offer wide array of creatures and servants (or masters) to be summoned into the Prime Material World, in search for new sensations, to lift their boredom and to further the goals of the Ecstasy.

Military

Succubi and Incubi - The far descendants of Procacitas. Masterful seducers, who have managed to practically weaponize their wiles. They are also among the most charming, intelligent and creative spirits of Ecstasy, whom can easily satisfy not only the carnal desires but also the more intellectual ones of all but the most picky of mortals. In most cases they don't even bother trying to corrupt anyone, as for them, pleasure of companionship (even intellectual) is its own reward.
On the other hand, they are also incredibly potent manipulators and plotters, whose spiritual hierarchy includes enough schemes and backstabbing to satisfy even the daemons of the Shadowlight Covenant. They do not take advantage of that with every summoner and every time they are summoned, simply because if they did, the amount of people willing to summon them would fall greatly. But an intelligent, funny and almost heartwarming companion with (most likely) no strings attached? That's the entirely different pain regimen.
It is said that some of them are in fact Dead in service to the Ecstasy that changed so much that they can no longer be distinguished from the spirits born from the deity of pleasure. It’s an achievement, in a way. The elder succubi and incubi are also capable of shapeshifting, which muddles the difference between these two subspecies while also making figuring their actual origin something complicated.
Stuporites - Shards of Desidius' power, his descendants and the ascended Dead in thrall to the Hierarch of Indulgence. They are beings in an almost perpetual state of barely conscious drug haze, kept that way by proper mixtures of drugs that are naturally existing in their bodies. When in combat and with said drug mixture altered to be one increasing their strength and resilience, they can be pretty terrifying.
They are as varied - if not more - than the succubi and incubi. Some are feral beasts, tearing apart all in front of them. Others are hulking and slow brutes, grotesquely altered by the drug cocktails (and sometimes merged with their armors), capable of squashing their enemies - though typically requiring allies to point them to their targets. Others are pretty much in an eternity-lasting state of lull, useless for anyone.
Ghouls - Servants of Cibus, Hierarch of Consumption, who gained a particular taste for the most forbidden type of meat - the one coming from the sapient beings. They are typically the most dangerous and intelligent among the spirits of Cibus, at least partially due to how limited in supply their food is (really helps with obesity issues) and how dangerous hunting it can often be.
Only low ranked ghouls will be ready to eat whatever falls in their hands. The higher in the rank, the most sublime their tastes - and the greater their power. Noble ghouls are all civilized, outspoken and powerful - which is pretty horrible for someone whose favourite (and in fact the only one acceptable) food might be a freshly harvested human brain.

Religion

High Gods

The religious head of the Rapturous Ecstasy is Procacitas, the Hierarch of Lust, the high god of lust and sex. However she is always described to be more of a co-head with Desidius, the Hierarch of Indulgence, the high god of laziness, drugs, and comfort, and Cibus, the Hierarch of Consumption, who is also the high god of hunger, overeating and cannibalism.
This triumvirate is however typically described as being mostly Procacitas-centered, with Desidius being seen as almost mindless and Cibus as being way too focused on overeating (to the point where he split into two halves that are continuously trying to devour each other). Procacitas, in the meantime, is apparently a devious plotter (as much as it is possible when it comes to omniscient high gods) who also has some long-term plan of establishing herself as the absolute center of the multiverse (although this is religion more than a confirmed knowledge.

The Fall

As one can imagine, the strongest point of the Rapturous Ecstasy is its insidious and corruptive nature. Everyone wants to have some happiness and comfort in his life. However, when one starts giving in to what gives them pleasure and makes that into more and more of a center of their life, the corruption of the Ecstasy starts painting their soul. When they accumulate enough of that, they Fall - and suddenly the pleasure becomes irreversibly more important than anything else in their life. They also become sympathetic to the goals of the Ecstasy and start doing their best to spread its malignant influence anywhere.
The secret pleasure cults of the Ecstasy are among the most common ones in the empire. What's more, they tend to be surprisingly devious and subtle, despite being a bunch of rampant hedonists. After all, many of them are highly cultured and creative - enough to appreciate and create various types of arts in their spare time when they aren't establishing paedophilic sex cults or hunting (and then eating) the most dangerous game.