Shin Megami Tensei: Digital Devil Saga

Without doubt the easiest boss in the entire game. Yes, Harley's back...kinda, seeing as he's dead.

ALL his attacks bar his normal attack are fire based, which means set up a fire shield (preferrably drain,) and you're laughing. He's also weak to ice, but is also not immune to anything, so you can pound away at him however you see fit. When he gets in the red he'ss use psycho rage, followed by an ice drain, then will waste his next three turns using fire storm on you. But seeing as he's not immune to any other spells, you can laugh in his face. Poor Harley, you have to feel sorry for him.