Devils are lawful evil outsiders native to the Outer Sphere plane of Hell. They typically obey a rigid hierarchy and base much of their dealing with others on strict contracts, always looking to get the upper hand on another in the process. It is common for devils to provide mortals with great power in life in exchange for an eternity of torment and punishment at that devil's hands in the pits of Hell.
Each of the nine circles of Hell is ruled by a different archdevil, a unique and nearly limitlessly powerful fiend. The most prominently worshiped and widely known of the archdevils is Asmodeus who is the only of them to attain full divinity. He is the master of the deepest circle of Hell as well as the entire plane. The other eight archdevils bow before him even as they plot amongst themselves to overtake his position and become the lord of Hell themselves. Cultists of these lesser archdevils are uncommon in the Material Plane outside of Cheliax, and even there they generally pale in comparison to the church of Asmodeus. Often, a worshiper of an archdevil is a lone cultist who practices his faith in total secrecy and lives a deceptively good life.