“The fool! The whole camp is looking for him!” whispered Osborn through his teeth. He and his changeling companion tracked the lost forester for a better half of a day, several miles into the dark Tesenvir Forest. And here he was, not lost or in any apparent danger; the young man stood several score feet away from them in the embrace of a naked girl.
The two stood in the center of a glade, up to their knees in fallen leaves of all the colors of the autumn. They seemed to pay no attention to their surroundings as they kissed; pale skin against leather jerkin, alabaster cheek against shaggy beard.
“Well, his mother will be relieved, I think.” said Vilas the Halfelf to his Easterling friend as they backed away from the clearing. “Although I doubt his bethroted will be very happy to… BY THE FURIES! Did she just bite his head of?”
Fthinoporinostrix. The name is hated by all the students of arcane lore who try to memorize it, but other than that is this fairy little known. The creature looks like a beutiful young woman with thick black hair and big eyes. Although it spends spring and summer in joyful glee just like its cousins, it has to hibernate during winter and for that it needs human blood.
When autumn starts, fthinoporinostrix seeks lone men and lures them in the forest, to its lair, a task which is made easier by a rotting smell that enthralls men (women however, find the smell vile and repulsive). When the fairy and its prey are alone, fthinoporinostrix finally reveals its true nature. Its body slumps to the ground yet its head springs forward on eight glistening black spider-legs. Its jaws open up to three times of the normal human span, revealing a set of sharp teeth. Everything is usually over in seconds. Then Fthinoporinostrix feeds, stores the blood in its body and hides the carcass, usually in its lair, along with any valuables the unfortunate wretch had on him.
Depending on its age, fthinoporinostrix needs two to five victims to collect enough blood to last the winter. It stores the blood in its human body (which is usually very skinny with the coming of autumn); should it lose this body, fthinoporinostrix will desperately try to “acquire” a new body from any young woman it can find. However, even if it succeeds, the loss of the original body always leads to the death of the creature within three days.
Armor Class: 9/4*
Hit Die: 2/2*
Attack(s): Teeth (1d8)
Saving Throw: 13
Special: Charm (smell, 50 feet, save negates), immune to Sleep and Charm
* number before the slash is for the human body, number after the slash is for the spider body
Note: I finally had to use at least some rules to sketch out the capabilities of the creature. As I neded something simple I used an oDnD inspired clone – Swords and Wizardry.