Forum:Help at end of W E 1

I can not kill Sargon (Soverign) at end of game. I came close once but have not since then. Is there or can anyone give me a suggestion on how to kill him? I'd appreciate it very much since I am waiting to complete Mass Effect beofre I go buy Mass Effect 2. I am around level34 or 35 with my Shepard. Please help!!!!!