Abomination Sickness is a metapathic malediction which affects the body through the soul. It can happen to anyone under the right circumstances, but spellcasters Psiolic are particularly prone to it.
As someone's Sanity wanes unchecked, the toll begins to affect their body as well. Their soul putrifies and their body warps, becoming a mangled echo of itself drawn from that person's nightmares. It begins as small details at first, but as soon as the Selschaeus begins exuding from their skin it quickly worsens.
What once had been a man was now a travesty. It crooned in pain, bloodshot eyelids sagging down over its cheeks and head tilted to compensate. A jaw worn down by bile and anxiety jutted out, offering a row of needles and knives.
It lurched forward on a leg too many, knees going out in odd directions and skin crackling like old parchment to reveal an oily flesh beneath. The scent bubbling up from its gut burned to inhale—to say nothing about what that bubbling putefaction might do to the flesh.
"Back away," the offworlder murmured, voice low and eyes wide. The hand bearing his sidearm trembled, not confident that the sidearm would put much of a dent in this creature.
Its milky eyes turned on him, focusing and finding nothing. It made another lurching step forward, a drumbeat rhythm of two knife-edged taps ending ine on resonous thud. The rest of it followed, teetering along on a spine which twisted like a serpent. In its gut, something was swelling, squirming like serpents.
"Get back! Get back!" I cried out, realizing then that the creatures slow pace was a ruse. It was too late—it came thundering forward, blossoming open into some terrible new configuration...