The Souleater literally eats souls. It will rip the avatar from a person and incorporate it into itself. The victim will be fully conscious during all of this, and will remain so for eternity inside the Souleater. The being slowly digests the minds and souls of its victims, an excruciatingly slow and painful process which takes millions of years. Their memories, skills and thoughts become part of the Souleater, while they wordlessly scream forever inside it. There is not even the oblivion of madness.
Fortunately, the Souleater seems to have great trouble manifesting inside the Gauntlet, or even inside the Horizon. It has been called the Lurker at the Threshold, ready to slither in whenever it can find a new opening. When it manifests in the physical world it quickly gains so much paradox it has to leave after a short time. It can however possess a person from the Umbra, and thus interact with the world. It is not uncommon for it to eat the soul of the victim, and then use his body as mouthpiece. The body spasms and is contorted by cramps while the being uses it. When it is done, it simply discards the body. When it manifests in the Umbra, it will look like a monstrosity without name or form. Its tentacles (?) are covered (or made of) screaming and pleading human faces, and apparently it has an eye. Apparently, because nobody has ever survived looking into it.
The Souleater is intelligent, but not in a human way. It thinks using all the minds it has ever eaten, knows everything they know and senses everything they sense. This makes it unpredictable and almost infinitely intelligent, at least in some aspects. Its personality, if it can be said to have one, is pure malign hunger. Since it cannot think well about anything it haven't absorbed, it must eat it to understand it. Its voice has been described as crude petroleum seeping through gravel. When it speaks, it seems to shift between the personalities of all its victims, sometimes talking imperiously, then childishly and suddenly completely normal. Most of the time it is completely incomprehensible, just a meaningless mass of screams, pleading and nonsense.
Fortunately, the being cannot rip away just any soul. To be able to eat the soul of a victim, the victim must somehow accept the Souleater. This can range from a symbolic gesture to a moment of understanding for the being. The important thing is that the victim has some kind of mental or emotional contact and acceptance of the being or a part of it (like a previous victim). That is enough for it to be able to eat the soul of the new victim. Using Mind on it is a bad idea. Another way it can gather souls is from dead and dying people who are much less resistant to its power. It is sometimes attracted by the death of many people, especially if it is a highly unnatural death.
Mages from the Celestial Chorus have discussed whether it is a kind of Anti-One. Unlike the One, where all avatars are harmoniously integrated the Souleater is a agglomeration of unwilling Avatars, a mocking parody of the true One. Some Euthanatos mages believe that the Souleater is the manifestation of the most intensely anti-entropic forces of the Collective Subconscious. Both groups agree that it must be hindered as much as possible and perhaps even defeated (but how that should be brought about is anybody's guess). Garou say that the Souleater is an aspect of the Wyrm.
Physical abilities: As much it wants to. When manifested, it can be as powerful as it need to be. When possessing somebody, increase strength and stamina by two and decrease dexterity by two due to the intense cramps.
Mental abilities: Practically all. Only the most recent victims skills and memories are clear, the rest are vaguely mixed together and may take some time to remember. When confronted to something normal or common, it can react quickly. When confronted to something unusual or unique, it has a harder time reacting. It has obvious problems with being social.
Magick: The Souleater can at least in theory use the magickal abilities of its victims, but it seldom uses other spheres than Spirit and Mind.
Arete: 8
Quintessence: Lots!
Mind: 6
Spirit: 5
Quote: "You! Here! How did you escape?"
"I took no notice. The geometries ceased to bind me. I came forth. I ate souls. Fresh souls, not the miserable plasma you have fed me all these years."
(Conversation between a technomancer and the Souleater, from the Illuminatus Trilogy)
Rote: Eat Soul (Mind 6 Spirit 5): The Souleater rips away the soul of a victim and incorporates it into itself. The victim will feel a horrible sensation of mental tentacles reaching out and pulling his soul from his body, into the maw of the being . If the victim fails to resist the Souleater his soul is absorbed. Otherwise, he is completely incapacitated by pain and the exertion of his fight for his soul while the Souleater tries to make him join it.
[The victim can resist using Willpower like any normal mental attack. The target number is 10, and each success will decrease the successes of the Souleater. If the victim botches, he will immediately be eaten, while if the Souleater succeeds, the target number is increased by the number of successes the next turn, when the fight goes on. In this way, the being slowly and painfully pulls his victim into him. Obviously, almost nobody can resist it.]
An important person, a friend of the characters or somebody with important information has become the victim of the Souleater, and the characters must find it, and then negotiate with it for it to either release the victim or tell them what they want. Are the characters ready to give the Souleater what it wants, or are they brave (and foolish) enough to try to trick it? And what about the victim?
A powerful Euthanatos mage (perhaps even an Oracle) believe he has found a way to fragment the Souleater and free the imprisoned souls. He want the characters to help him with the necessary preparations. They might find unexpected help from other groups, even the Technocracy, in doing this. However, the Souleater is immensely powerful and will doubtless know about their plans. What if the mage is wrong, and fails? What if the Souleater turns out to be a necessary protection from something even worse?