The objective is not to destroy the Entity. The main gaol is to remove the sword fragment for the machine directly above the Tesla turret. Ignore the Beast the entire time. First, pull the four levers around the room. They are on the outer wall and easily accessible. Then, hop into the Tesla turret. If you get knocked out of the turret, hop back in, healing as needed. Here you must use the turret's "repel" function to launch the four lowered Tesla balls into the beams of energy. Do not use the "attract" function as this will just slow you down. After completing the entire circuit, wait for the electricity to die down, then do it again. When you complete the circuit the second time, get out of the turret, switch to first person view and use the grapple on the sword fragment and pull it out.