Archdevil

Archdevils are powerful, unique devils. The position of archdevils in the hierarchy of the Seven Hells is clear; archdevils are the most powerful and are, therefore, on top. Each Archdevil rules over one of the seven layers of hell. The hierarchy is ever-changing, as the archdevils and their subordinates keep plotting against each other and keep betraying one another.
Archdevils approach close enough to divinity that they cannot cross portals to toher plane on their own, though sufficient mortal magic can summon them.