When you are attacked by the Super Beast, morph into the alien. Shoot parasites and melee
him until he calls the first wave of aliens. Use the BBG to kill these aliens (alternately
stay in the alien form), but watch out for the Super Beast. If your health gets too low, 
switch to human and wait until it is safe to return to alien form. Using alien mode is 
safer because every time you attack the beast your health will refill.