The last boss has a few abilities to avoid. If you are within the level range to actually take him on then here are some suggestions:
*Use Talos, he heals and has a carbonite spray interrupt that is useful for this fight.
*Interrupt the boss heal any chance you get
*You don't have to interrupt force storm, just avoid it. Also, if possible, have your companion avoid it too by switching to passive as soon as he starts channeling and run away then turn it back to aggressive.
*Use the max dps rotation for long fight encounters for your build. You need to be regenerating force power since this fight may take awhile and you will need to help Talos heal on occasion.
Otherwise if you are still having problems, bribe a player on Voss to help you out. 2 players and 2 companions make this fight look like child's play.
Hope these suggestions helped.