The Rift - Shifting Caverns

The deep fires have risen closer to the sunless lands in these parts. Rivers of magma warm the warren of tunnels and provide a diffuse red glow that illuminates much of The Shifting Caverns, along with the usual biolumescent flora and glowing mineral deposits. The land is unstable with passage-riddled mountains shifting and jostling each other as they ride atop the flows of molten rock far below. Denizens of the underneath who know the way can use these passages to reach many of the portals to the great cities of the sunless lands, and the dark homelands of the Goblins and Drow. Passages to much of the the surface world can be found, as well, have yew a cunning guide. The life-giving deep fires make these tunnels fertile. Falling cataracts and rising steam geysers circulate nutrient-rich waters through the caverns, from which spring all manner of flora and fauna. There are a few settlements in this strange land, but frequent earthquakes and collisions between the drifting cliffs mean that most structures and enclaves are temporary, lasting less than a handful of centuries. Furthermore, the peoples of the underneath have long kept agreements that the Shifting Caverns remain neutral ground owned by no lord or empress.