Underdark

Existing far below the surface of the world's The Underdark is a vast subterranean region that exists below the surface of Valier. A dark and hostile place, the Underdark is almost a world unto itself, with civilizations, monsters, politics, economies, and threats that may interact only sporadically or indirectly with the surface world.

Entrances to the underdark are seldom found or used,