The goal is not to destroy the Entity, actually. The main objective 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 are 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. Once you have completed 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, then use the grapple on the sword fragment and pull it out.