In Mission 4: Safeties Off, look for Thor's Hammer in the shallow water, near some mines and between two building south of the "Avoid the CELL Searchlights and Make your way to the Park" primary objective. The hammer is exactly 81 meters away from the primary objective when looking back at the waypoint. When you pick up the hammer, electricity will surge through your body. It can be carried like a piece of debris. Throwing the hammer at CELL soliders will instantly kill them.