The Styx Fountain periodically opens in an underground lake beneath the Athenas Daggers. It has the appearance of a black geyser of inky water, spewing up from the murky depths of Maitimírë. It turns the surrounding waters into a thick, greasy soup of alien ichor. These otherworldy waters taint the rock for many miles into the Underdark. The rocks that survive the taint, and don't become too weakened, become known as Styx Granite.
Entering the Styx Fountain will take a traveler into a inky canal leading into a permanent gray fog faintly lit by ghostly lichens. This canal flows into the river Styx. There is no boat, so travelers usually row into the fountain. After entering the Styx Foutain, travelers have left the world Bal-Kriav and entered the world Oinos of the Gray Waste system.