he Abyss is not truly part of the mortal world at all, but is the extraplanar home of the demon races, spawn of uttermost evil. In ages past, powerful mages created the Portals, mystical gates to this vile place, the better to summon their denizens to serve them. The demons seized their chance to pour into the mortal lands, and caused much devastation before they were at last repelled. The mages who created the Portals are long since dead, but still the Portals remain—although now battle-hardened human warriors guard them against incursion from the far side.

The Mini Abyss is most directly reached via the western Portal, found in a cavern far to the west of Nevrast and barred by grim veteran guards, virtuous warriors of good who protect the western lands against incursion from beyond. The settlement of the Vale is close by, and thus a fresh invasion of demons would be devastating. Beyond the Portal lurk lesser minions of evil: the vicious dark elves called drow—not all of whom are in the Underdark—and bloodthirsty minotaurs. Beyond these foot-soldiers of evil are the true denizens of this place—demons. These terrible beings guard the third Portal, which leads from the Mini Abyss into the Negative Plane, from which an explorer can enter the Abyss proper.

In recent years, a small group of elementals who have broken free of the control of their mortal mage summoners have made their home in the caverns nearby, drawing strength from proximity to an interplanar conduit such as the Portal, while not wishing to return to their own home planes. These magical beings are neutral in outlook, caring neither for the human settlements nearby nor for the demons and lesser fiends of darkness beyond the Portal, wanting only to be left alone, but are fierce in defense of their adopted homes.