Now you (hopefully, if you've been following this Resident Evil 7 guide) have got the shotgun and the scorpion key, it's finally time to get that last Dog's Head we've been after – but first there's a few more Molded to deal with, and another battle with Chainsaw Jack himself.
If it turns out you can't get this far, yet, head back to the main Resident Evil 7 walkthrough and step through our previous guides to get you chainsaw-ready.
Back in the Processing Area, head towards the Boiler Room – investigate the bathtubs on your route for consumables – we found some handgun ammo and Chem Fluid – before continuing up the small set of steps. As you do so, two more Molded will make their presence known; one in front of you, and one in the corner from where you entered the room. We recommend retreating to the doorway you came in from to dispatch them so you don't get caught between them. It's also possible to only trigger each one at a time if you're extra cautious.
However you choose to deal with them, once they're taken care of head into the next room with a pair of giant boilers. Three more Molded will spawn in this room, so deal with them as you see fit – feel free to retreat into the previous room if you need space. If they're a little too fast for you, then you can shoot their legs to slow them down and give you a bit more breathing room, but headshots will do the most damage. Your new shotgun will take them out pretty swiftly, or if they get too close, though it'll save you ammo if you use the handgun when they're at a distance. Once the room is clear, search for any pickups – there should be some Strong Chem Fluid in one of the lockers – then go through the door with the Dissection Key.
Right on the shelf in front of you as you go in, you should see the final Red Dog's Head – attempt to take it, which will trigger a cutscene in which Jack takes the head right from under you, though he fortunately doesn't seem to be aware of your presence yet. When you regain control, grab the Shotgun shells from the right locker, some more in the breakable box down the steps along with a herb and then go through the door.
You'll see the Red Dog Head hanging suspiciously invitingly in front of you – before you grab it, explore the surrounding rooms for more stuff – we found Chem Fluid in the room on the right, and some Gunpowder under the stairs. When you're ready interact with the Red Dog's Head and prepare for another boss battle with Jack.
How to defeat the Chainsaw Jack boss in Resident Evil 7
Once you're down in the arena, you want to once again keep your distance from Jack as best you can. Kick the hanging body bags into his path to stun him temporarily, especially when he's about to attack. Either keep this up for a while, or hurry the next stage of the fight along by shooting him a few times if you're not fussed about ammo – and eventually he'll run over the fence at the back, rip it open and pull out a pair of what seem to be Chainsaw-powered Shears.
Once Jack does this, it's your cue to – while still avoiding Jack's attacks – get yourself to where he got the shears from. There you'll find a chainsaw of your own to grab, so get it and pick it up, and now the fight can really begin. Keep more or less the same tactics as before – bearing in mind Jack's weapon does allow him to cut down the body bags, so they'll deplete in number – but this time when he's stunned, go in with your chainsaw.
After a few good hits on him, Jack will go down on one knee and start mutating. That's your cue to run in and go to town on his mutated point with your chainsaw. Keep this up a few times, and you'll eventually best him and he'll go down for good – but if you're struggling there is a First Aid Med in the corner of the arena you can grab and use. Once Jack's down, head towards the barred door and interact with it to cut it open with the chainsaw.
Now you can return to a safe room to save and heal up, then return to the Main Hall with the Red Dogs head to open the door and finally head outside to the rest of the estate and the next part of the guide.