OK, I'm on the boss in Level 9: Xixor's Palace. Whenever I try to beat him, he just quickly kills me!!! Is there an easy way to beat him without dying?

I just kept firing disruptor shots at it. Each round takes off about half or 3/4 of a phase's energy. Heh, the last time I defeated it was sick. Destroyed all but its head with about half of its energy remaining and it managed to hit me with its laser, which brought my health to 0. But I just barely managed to get off a shot before dying and the boss' energy dropped down to 0 as well. The game hung for about five or seven seconds and then brought me to the next stage.