You must make noise to defeat Venom. Hit him once and Sandman will raise his fists off the ground in an attempt to crush you. Dodge this by simply running through either of his fists. Harry will throw a grenade. When it explodes, it will stun Venom for a few seconds and make him vulnerable to all your attacks. Note: You must be nearby when the grenade explodes; it does not seem work when you are not there. Also, there are health packs on the two sides of the building that respawn once you use them. If you are lucky, two may appear in the same location, doubling the health you can get.