It's speculated when Richa planting the seeds of life into Tor'Dath, she unintentionally created the fungus spirit Zuggtmoy.
It's said that Zuggtmoy shares "her gift" to those truly desperate for power, but don't know to commune with the spirits of the world. Though the methods of possession and the unique properties through the corruption of her powers her gift is incompatible with life granted naturally. Thus many of the recipients of "her gift" often die as they grow in power.
When "her gift" is granted Zuggtmoy injections a special fungus into the body of the recipient massively increasing the 6th sense so one can tap into the leyanic magics of Tor"Dath
The Demon Queen of Fungi, Lady of Rot and Decay, Zuggtmoy is an alien creature whose only desire is to infect the living with spores, transforming them into her mindless servants and, eventually, into decomposing hosts for the mushrooms, molds, and other fungi that she spawns.
Zuggtmoy is utterly inhuman, but she can mold her fungoid form into an approximation of a bipedal shape, including the skeletal-thin figure depicted in grimoires and ancient art, draped and veiled in mycelia and lichen. Indeed, much of her appearance and manner, and that of her servants, is a mockery of mortal life and its many facets.
Zuggtmoy’s cultists often follow her unwittingly. Most are fungus-infected to some degree, whether through inhaling her mind-controlling spores or being transformed to the point where flesh and fungus become one. Such cultists are fungal extensions of the Demon Queen’s will. Their devotion might begin with the seemingly harmless promises offered by exotic spores and mushrooms, but it quickly consumes them, body and soul.