This is a multi-stage fight against a heavily mutated Jack. He has multiple eyes/weak points that glow yellow. In the first stage, use the Shotgun and Grenade Launcher to destroy these eyes. He'll charge and try to grab you. In the second stage, he'll grow a massive arm. Focus on the large eye on his back. Stay mobile, use the pillars for cover, and don't be afraid to use your most powerful weapons. This is a battle of attrition.
