Herthers appear vaguely like a mixture of a goat and a wasp. Their hairy bodies are more or less like that of goats with four twice-jointed limbs jutting out at odd angles. Their arms and legs, as they might be called, end in cloven hooves, covered in thorny protrusions. Their heads are shaped like that of a goat and are covered in short gray or black fur, but mounted above its fanged mouth are two red bug-like eyes.
Herthers are intelligent and can think and learn and reason, but they do not speak, though they can understand any language. Herthers run on four legs like hounds.
Herthers can be found on the mortal coil only when they are summoned here from the plane of nightmares, Gluush, usually by one of the cults of Igg’soteku, their master. When brought to this world, Herthers are not in any way under the control of the summoner, unless wood from the rowan tree is used in the summoning, as it is a potent protection from evil spirits and creatures. The rowan wood binds the Herthers to the summoner’s will. When the rowan is remembered, Herthers are often sent on missions involving killing and/or spreading some sort of plague. When the mission is finished, the Herther is given its reward, usually a human life, but for a more difficult job the Herther may ask for something better (or worse, depending on your view) such as a specifically god person or a whole village. When the rowan is forgotten, however, things are more disastrous. The summoner is quickly eaten or Changed (see below), and then the Herther will wander around doing whatever causes the most damage until it is stopped, usually by a band of adventurers.
Sometimes, when they are feeling particularly despicable, Herthers will not just kill their victim outright, but instead will Change them. This process usually takes two Herthers, since the victim will need to be held down. The Herther begins by mutilating the victim, slicing off lips, cutting into the body, and crushing the hands and feet beneath its hooves.
When this is finished, the Herther opens one of its own veins and forces the victim to drink its pale blue blood. The other worldliness of the Herther’s blood along with the trauma and pain of the maiming, drive the victim into a strange kind of insane frenzy and warp their bodies into foul things. The lip less mouths grow sharp fangs that drip venom. The cuts bleed yellow pus, and the mutilated limbs coagulate into meaty bludgeons.
Though most that know of it fear the Change, but some of the more perverse cults of Igg’soteku covet the status of a "Chosen of Igg’soteku" as they call it. They will often summon Herthers specifically to undergo this horrible change.
In addition, some enterprising cultists have hypothesized that it may be the blood of the Herthers itself that creates the Change, and it simply uses whatever pain the victim has suffered and use it to mutate them. These few have come into possession of a quantity of Herther blood (most likely by summoning and killing a few), and are performing experiments on abductees. So far, they have had very little success, but that will not necessarily last forever.