Mirror of the Serpent People
The Mirror is an ancient tablet inscribed on the back with a summoning spell.
The mirror is a small triangular tablet "and was broader at the widest than a man's heart." One side is blank acting like a mirror, and the other has rows of Serpent People lettering, cut into the metal with some sort of acid. The tablet is some sort of heavy metal. The mirrored side is said to distort the person's image "like the drawn, pallid features of the dead."
The inscription on the back, after being decoded from the Serpent People text can be discovered as a summoning spell. This spell will call a completely invisible being of no conceivable origin. No magical means have been discovered to reveal its presence before it begins attacking its summoners. Its presence can only be noticed by its shadow, which seems to follow and slowly gain on the shadow of the magician who called it. No control or dismissal spells appear on the tablet. When the shadow reaches that of the magician the magician is taken over by the creature and slowly morphs into an inhuman version of it. The thing appears "flowing as of some heavy, thick, putrescent liquid; and its color was not blue nor purple nor black, nor any other hue to which man's eyes are habituated, but a hue as of some unearthly purulence; and its form was altogether monstrous, having a squat head and a long, undulant body, without similitude to beast or devil."
Avyctes found the tablet washed up on the beach near his home and endeavored to unlock its mysteries. After using the soul of a prehistoric sorcerer named Ybith to discover the origins and language of the Serpent People Avyctes used the incantation on the back. The spell was carried out around a triangular shape drawn with the blood of birds by Avyctes, Pharpetron, and the mummy of Oigos, an Atlantean warrior. But after some time nothing seemed to happen. After some months Pharpetron saw the shadow approaching that of Avyctes and soon the magician his apprentice and the mummy were all transformed into images of the shadow.