Acamoth are abyssal entities that dwell in the Fallen World and strive to return to the unreality that birthed them, as opposed to Gulmoth, which are invaders from said unreality who will return in time after wreaking havoc. Lacking enough power to do so on their own, they make pacts with curious—or infernal - mages. They bargain to act as guardians and guides, offering substantial knowledge of lost secrets and raw power. In exchange, the acamoth use the astral dreams of Awakened souls to contact the void that rejected them — the Abyss for which they continually yearn.
The pact gives an acamoth access to the mage's Oneiros, where it conjures nightmares so that it might again experience the caress of the Abyss. Only through an Awakened soul's Oneiros (and the Temenos) can an acamoth reach out to its home. Acamoth nightmares are full of damnation and revelation and play off a mage's Vice: apocalyptic plains for the prideful, slaughterhouses for the wrathful, murderous, writhing orgies of flesh and blood for the lustful, and far more sinister variations. As exchange, the Acamoth grants certain investment to the mage, strengthening his grip on the mage's soul and degenerating his Wisdom.
Because acamoth were spawned from the Abyss, few records exist of their true names, preferences, treachery, or weaknesses. Scheming in restless sleep, they writhe in pockets of the Shadow Realm. When their offers of power and aid to the magically inclined are accepted, their appearance slowly changes to represent the Vice or perversion the demons represent. As the acamoth's astral dream unfolds, it slowly reveals its true motivations in its very appearance, becoming more demonic, infernal, and hideous in its strength.