This grotesque creature is your first major boss encounter, typically found at the end of Chapter 2: The Hospital Ward. It's a hulking mass of flesh and medical equipment, slow but incredibly powerful. You'll face it in a confined operating theater.
Phase 1: Initial Assault
The Abomination will slowly lumber towards you, attempting to swipe with its massive arms. Its attacks are telegraphed but deal heavy damage. Your primary goal here is to create distance and expose its weakness. Notice the exposed, pulsating sacs on its back. These are its weak points. You'll need to lure it past the large surgical lights hanging from the ceiling. When it's directly underneath, interact with the control panel on the side of the room to drop a light, stunning it and exposing its back. Use your Revolver to shoot the pulsating sacs. You'll have a small window before it recovers.
Phase 2: Enraged State
After taking significant damage, the Abomination will become enraged. It moves slightly faster and will occasionally charge, breaking through obstacles. It also gains a new attack: a short-range bile spit that causes a temporary blur effect on your screen. Continue to use the surgical lights to stun it. You'll need to drop at least two more lights to expose its weak points enough times. Conserve your Revolver ammunition for these critical moments. If you run out of ammo, the Rusty Pipe can deal minor damage during stun, but it's risky. Focus on evasion and precise shots. Reward: Access to the lower levels.