<P> To save their lives, Tenacious D challenge Satan to a "rock - off", which he cannot deny, as the "demon code" strictly forbids him from declining such a challenge . As the bargain goes, if Tenacious D wins, Satan must return to hell on his own and pay their rent . But if Satan wins, he gets to take KG back with him as a sex slave . Ultimately, they lose (KG sings, "That was a masterpiece! / He rocks too hard because he's not a mortal man ."), and Satan attempts to shoot KG with a bolt of energy . JB jumps in the way, and the bolt bounces off his guitar, blowing off a piece of Satan's horn . JB is able to send him back to Hell with a magical incantation . (As explained earlier, should Satan become "incomplete", he can be banished from the Earth with said incantation .) </P> <P> The two turn Satan's horn into the "Bong of Destiny" and the movie closes with the two smoking from it as they write new songs . </P> <Ul> <Li> Jack Black as Jack "Jables / JB" Black <Ul> <Li> Troy Gentile as young JB </Li> </Ul> </Li> <Li> Kyle Gass as Kyle "Kage / KG" Gass </Li> <Li> JR Reed as Lee </Li> <Li> Ronnie James Dio as himself </Li> <Li> Dave Grohl as Satan </Li> <Li> Ben Stiller as Guitar Center Guy </Li> <Li> Paul F. Tompkins as Open Mic Host </Li> <Li> Tim Robbins as The Stranger </Li> <Li> John C. Reilly as Sasquatch </Li> <Li> Meat Loaf as Bud Black </Li> <Li> Cynthia Ettinger as Betty Black </Li> <Li> Andrew Caldwell as Billy Black </Li> <Li> Amy Poehler as Truck Stop Waitress </Li> <Li> Colin Hanks as Drunk Frat Dude </Li> <Li> Amy Adams as Gorgeous Woman </Li> <Li> Gregg Turkington as Stand Up Comic (credited as Neil Hamburger) </Li> <Li> Evie Peck as KG's Mother </Li> <Li> Jason Segel as Frat Boy #1 </Li> <Li> David Krumholtz as Frat Boy #2 </Li> <Li> Fred Armisen as Security Guard #1 </Li> <Li> Ned Bellamy as Security Guard #2 </Li> <Li> Jay Johnston as Gang Member #1 </Li> <Li> John Ennis as Gang Member #2 </Li> <Li> David Koechner as Surplus Store Clerk (deleted scene) </Li> </Ul> <Li> Jack Black as Jack "Jables / JB" Black <Ul> <Li> Troy Gentile as young JB </Li> </Ul> </Li>

Who played the devil in pick of destiny