The worm moves left and right at the beginning to confuse you on which side he will be attacking from. His weak point is in his mouth. Use the assault shotgun, Magnum, rocket launcher, or MRL. Dodge his underground attack. When he comes back up, you’ll look up into the sky. Shoot the rocks coming down and repeat the process. He will jump into the air a few times also. Shoot his mouth to send him flying to the side. Once his health gets down to half, shoot four MRL rockets into is mouth. If he lives, finish him with the assault shotgun. Note: The bus that he throws when tossing cars will take out half of your health. Make sure to shoot the bus and other vehicles to make them explode.