A green, skull-like guitar pick fasioned from one of Satans teeth. It granted the user supra-natural rock and roll abilities. Satan recently recovered this item, although he lost his right horn in the process. The horn was later shaped into a bong. The last owners of the PoD were Jack Black and Kyle Gass (Tenacious D).
I just bought Tenacious D in the Pick of Destiny on DVD. It is fuckin' hilarious.