The Unholy Throne.

The Unholy Throne,  a great seat made of onyx, obsidian, and basalt, is a legendary, and most evil, artifact in existence.  It is said to either reside in the Mountains of Dusk, or in Durthinngar, or in Bane.  Finding the Unholy Throne has been the goal of most great villains; such as the Witch King, the Shadow, Lord Felrad, Zia, and so forth.  The power of the Unholy Throne is that who ever masters it, and sits on it, controls all the forces of evil.  The Throne was made on Null, by nuraza and anuli smiths, and imbued with it's power by a group of thirteen warlocks.  The Unholy Throne is evil's greatest strength, and weakness, since evil fights evil, the Throne brings together all the vile creatures under one banner, but once the user of the Throne is killed, evil then continues to fight evil.  It was used long ago in the Demon War, a dunruvali (demon) called Zargath used the Throne to win the war, but then Otorin Derenson killed Zargath's body, and the Throne was, hidden and lost.