This is continued from the Deathclaw Research Lab section of Fever Dreams.
The player will pass through a few hallways and then find themselves in a high-ceilinged room with several bright lights in their face.
As they near the lights, they'll see a doorway to their left. As they approach it, Pike will begin speaking to them over an intercom, warning the player that something is still there.
As the player passes through the doorway, they’ll be immediately attacked by a Deathclaw labeled “Jeffery” with an animation. During the animation, the player’s vision will blur signaling another hallucination and the Deathclaw’s head will explode into gore.
As the player fights the headless Deathclaw, their vision will remain blurred on the edges and they’ll cycle through complaints of their head hurting, and shock that the Deathclaw is alive at all.
The Deathclaw will periodically cloak itself and trigger explosions to make it difficult for the player to trace exactly where it is.
After the Deathclaw is defeated, a confetti explosion will emerge from it - a further indication this whole thing is a hallucination. The player will suffer another FEV attack and fall to the ground in an animation. Their screen will fade to white.
The player will awaken, they will still be on the ground, and Pike will be over them with a gun. From this perspective, the player will have a conversation with Pike.
At various points prior to this, the dialogue choices the player has made will have been tracked, determining a score that leads to a Positive, Neutral, or Negative ending. For a full breakdown of the choices involved, see Affinity (Spoilers).
Depending on how the player interacted with Pike, he may give the player a passphrase to say to Dolores.
Eventually, Pike will transform into a Behemoth-like mutant, rip a piece of machinery out to use as a club, and attack the player - using the club if close, and throwing rocks if the player stays far away.
This is the final boss fight.
Halfway through the fight, Pike will drop down to a bleedout state and begin speaking as if he’s regaining control. One of three things will happen, depending on player’s status with Pike.
Positive: Pike will tell them there’s a gas system that can be released to end him and will give the player the password to enter the room nearby and activate the gas. The player can then use the terminal to open the door and another terminal inside to trigger the gas, killing Pike without any further fight.
Neutral: He’ll call out to the player asking to be put out of his misery, but otherwise the fight continues as normal.
Negative: He’ll become enraged, yelling at the player and will receive a buff that causes him to deal poison damage to the player - making the fight more difficult.
After Pike is defeated, the player’s objective updates, and now their overarching objective to find the second Antiviral dose updates to point to Pike’s body. Looting him will give the player a keycard; this updates the objective marker to point to a marker past an exit sign.
After the door in this sign, the player will find a pressure plate. Standing on this in Power Armor will cause the door to seal shut. The player will need to leave the Power Armor behind to proceed to the Medical Research Lab.