So you've decided to go after that evil Emperor huh? Yeah, I can't stand him either. Keep at him close with lightsaber attacks, dashing in when necessary to keep him from running away. When he starts glowing purple and gathers some debris to toss your way, run towards the bottom two panels and stand behind them for cover. Most, if not all the debris, will miss you and hit the cover instead. Once you see that he's out of ammo, rush back and start wailing on him. Keep an eye on his lightning attacks as you draw close, block them and it'll go back to him in some instances. When he summons his cronies, use Force Grip or Dash to send them flying towards the destructive barriers (avoid them, they hurt!) and watch them burn. Follow this pattern as The Emperor goes through his cycle of tricks and you should be good to go.