This code explains how to defeat the Prophet Of Regret on Legendary simply and easily. Kill the Honor Guards near the entrance (Plasma Grenades would work good because they are usually bunched together) but watch your back because they are wielding Energy Swords. You will see the Prophet floating at the end of the room. Charge at him and he will yell for the guards and start firing at you with his laser beam (or whatever it is) just board his chair and punch the hell out of him until he dies. Then jump off his chair and wait and the video will start and the level will end.