Step 1: Turn on Power

Step 2: Locate 3 keycards on the bodies of scientists (1 in spawn house, one outside spawn house courtyard, one in upstairs section of second hellhound) the third keycard will always be the one to unlock the underground lab

Step 3: Turn on the generators according to the code at the lab entrance (top right corner before entering main lab)

Step 4: Turn on 5 switches to open pap (located in Lab, no particular order)

Step 5: Locate 4 Nova canisters, bring them PaP (one at a time in solo) and activate the teleporter to receive dialogue.

Step 6: Build the shield (One part found outside in random locations, second part given after dialogue is finished.

Step 7: Use the shield on a door upstairs in spawn house to find a blue orb, shoot and follow orb until it goes into the PaP room MPD object.

Step 8: Get AAT kills near the canisters around the map

Locations:
Fireworks - Near Speed Cola
Blast Furnace - In PAP room
Thunderwall - Near entrance to labs in sewer
Turned - In parking garage
Dead Wire - Next to power building

Step 9: Place the crystals gained into the crystal containers across from pack

Step 10: Grab Vrill device and place in MPD in pap room

Step 11: Grab the Nano Suit

Step 12: Upgrade Hell's Retriever by getting a good amount of kills then finding 6 red glowing skulls around the map, then entering a portal in the room above spawn, and filling the soul box(es).

Step 13: Jump into the high balcony with the blue electricity symbol, then grab the last part of the Sliquifier using the Hell's Redeemer

Step 14: Use the Sliquifier to fill the tubes in the lab hallway (Similar to the Ball step from Die Rise)

Step 15: Use the hacker (There are a few spawn locations, all in the labs) on the panel next to the Plasma Rifle, then hack 4-5 of the moon panels around the lab

Step 16: Go back to the panels to the left of the Plasma Rifle and interact with each one. The black case on the table nearby should open revealing a fuse.

Step 17: Find the button in the hallway next to the Plasma Rifle that says START LOCKDOWN and survive the lockdown to gain 1 Portal Fuse (Buttons are player specific, each player needs to interact with the one that says start lockdown)

Step 18: Do the Samantha Says in that same room to gain the last Portal Fuse

Step 19: Get ready for a miniboss. Put all 3 fuses inside the fusebox near the teleporter. Once you've done that, a mini boss will spawn. Kill it to receive the Elevator Key (the elevator is located in the parking garage area, where the Turned canister is).

Step 20: Complete the flytrap EE to get the BFG 9000

Step 21: Once you've taken the elevator down, you will begin a rune deposit mission. (Similar to Vanguard Zombies) You will have to kill zombies and pick up runes (you can only hold 5 at a time) then deposit the runes into 4 separate pillars. Each pillar holds 5 runes. Once you've finished that an 'energy source' will be released and you will have to shoot it with the BFG.

Step 22: Go through the portal that you opened with the fuses earlier in the egg. You will be teleported inside a house in a 'different dimension'. Exit the house and book a hard right; you will see a white orb. Go up to it and hold F to interact and begin an escort mission. NOTE: This one takes A WHILE.

Step 23: The escort will turn into a soul box. Fill it.

Step 24: Once the escort is finished head back outside and stand on the green portal looking circle out front. You will essentially be 'capturing' it, kind of like the generators from Origins. There will be multiple spots you need to go to. The order will be different each run.

Portal 1: Outside Church/MPD building in 'different dimension'.
Portal 2: Near the courtyard outside of the spawn building
Portal 3: Next to the bus near the drop down to the sewers.
Portal 4: In front of the building next to Speed Cola.

Once you've captured all 4 portals, you will need to use the Maxis Drone to pick up the last energy source and transport it.

Step 25: Return to the PAP room and talk with the AI

WARNING: This is entering boss fight territory... Make sure you are as kitted as you can be and have LOTS of ammo.

Step 26: Use the hacker to hack both computers surrounding the portal in the lab. When you do, the Butcher from Diablo will spawn, and you will have to take him out. He will teleport somewhere else on the map, but he will be marked so he's easy to find.

Step 27: Once he has been eliminated, collect the Soul Canister and bring it back to the AI

Step 28: Bring the canister through the hacked portal and place it on the teleporter pad. This will initiate the THREE STAGE BOSSFIGHT. GOOD LUCK.

Step 29: Once you have defeated the Khan Makyr 3 times, you will need to be ready to get to the Gazebo of the final arena and press a button. You will have a limited amount of time to do so, or her health will reset to half.

Step 30: ESCAPE and enjoy the ending cinematic!!