Four Against the Netherworld: A Supplement for Four Against Darkness

From BoardGameGeek:

Abandon all hope! Four Against The Netherworld is a supplement for Four Against the Darkness, for character levels 6-9. In its pages you will find: New classes: Demonologist, Cambion, Cleric of Zur, Cleric of Foryos, and a reworked Paladin; A complete economic system for the Netherworld; Rules for hex-based exploration, with plenty of terrain types, and a downloadable color map of the known regions of the Netherworld; Six new spells for wizards and cambions; New Reactions: Burn Souls, Capture, Conversion, Demonic Pact, Mercenaries, Demand Obeisance, and more; Tables to generate encounters and events; Plenty of new, deadly monsters, including randomly generated Lovecraftian aberrations. This is not a stand alone game. To use it, you need a copy of Four Against Darkness and Four Against the Abyss.