The Doomsday Heist Act 3 (Doomsday Scenario) Full Guide


This is our guide to Act 3: The Doomsday Scenario of the Doomsday Heist for GTA Online. We also have guides for Act 1: The Data Breaches and Act 2: The Bogdan Problem.

The Doomsday Day Heist Act 3 is called 'The Doomsday Scenario' and has 5 setup missions, each having their own prep missions and leading up to the finale called The Doomsday Scenario. The prep and setup missions in Act 3 are relatively easy, however the finale makes up for that! The setup cost for Act 3 is a hefty $120,000. The reward you get is pretty good considering the setup cost though. This is the final Act of the entire 'Doomsday Heist'.

Doomsday Heist Payouts

  • Payout (normal): $1,200,000
  • Payout (hard): $1,500,000

Prep 1(a) - Marked Cash

There are two prep missions for the first setup mission - one of them is called 'Marked Cash'. In this mission you will be instructed to collect a duffel bag which contains a huge sum of money (later to be used to rescue Agent 14). We recommend you have either a Buzzard or an Oppressor Mark II so that later you can escape the cops easily.

Once you reach the location, you will need to get the duffel bag, and as soon as you collect the bag you will have a 4-star wanted level on you. You can easily escape the cops by either calling Lester or by flying away back to the Facility with the money. Just try to avoid the vision of cones of the cops.

Duffel bag containing the money

Prep 1(b) - Recon

This is the second prep mission for the first setup. You need to go to the Pacific Allied Shipyard and take pictures of the whole area including sections such as the west door, east door, upstairs room, etc. Simply bring up your phone and take picture of the required place. You will see little camera icons on your mini-map showing the location of the places you need to take the pictures of. After taking a picture you simply send it to Lester. Once you're done, you can leave the area to complete the prep mission.

Picture of the main gate taken

Setup 1 - Rescue Agent 14

This mission is tough, but not as tough as some make it to be. Make sure you have a full stock of snacks and armor, and you'll also need an Armored Kumara and a mini-gun (super important). Armored Kumara will make this mission a cake walk for you.

Before heading to the shipyard, ask your friend to sit with you in your Armored Kumara. It will make it much more convenient to go through this mission.

Head over to the shipyard and when you get there, you will immediately enter a gun fight. Take out all the enemies outside and then head inside the warehouse through the big north entrance.

Stay inside your vehicle and take out all the enemies. Once you've killed them all, head over to Agent 14 and a cut scene will play, showing AI Juggernauts appearing from the north entrance you entered from. Quickly take cover by the wooden planks on the left hand side and switch to your mini-gun.

The Juggernauts are going to be invisible so switch to your thermal vision (don't worry it will be available once the Juggernauts arrive) and take them out using your mini-gun. An essential tip here is that you need to stay behind the wooden planks and slightly move towards the edge, just enough so that you can see the Juggernauts and aim at them.

Another trick is that you will be able to shoot through the planks you're taking cover behind, and this way the Juggernauts will not shoot at you, since they cannot see you. Aim at their heads and shoot. They should die after 2-3 seconds. Be very careful not to go in front of them though, as they will insta-kill you and are extremely powerful.

Killing the guards in front of north entrance of the shipyard
Killing the first set of Juggernauts coming from the north entrance

As soon as you've killed all three of them, quickly switch to a normal gun, run past the planks and you should see a door to your left. Go through it and go all the way to the end of the warehouse as four more Juggernauts will spawn at the back. Ask your friend to stay in cover to avoid getting shot at. The Juggernauts will be focused on your friend, so you can go behind and take them out easily. They will see you if you are not in cover though, so still take them out while in cover.

Door to the left past the wooden planks
Killing Juggernauts at the back (south)

After killing these Juggernauts some more enemies are going to come through helicopters. Quickly head back into your Armored Kumara and ask your friend to do the same. Once inside, take out the incoming enemies and drive to the next point.

As you head over to the next area while clearing all the enemies, two more Juggernauts will spawn. You can easily take them out as well since there is a little gap in between the two containers to their left side. Just aim through that and kill them both. Go back in your Armored Kumara and continue forward.

Sitting back in the Armored Kumara and taking out the enemies which the helicopters dropped

Now you will be the last area where you need to clear some more enemies, and of course two more Juggernauts will spawn. Stay in your Armored Kumara and get behind one of the big stones in the area. While you're inside and covered, switch to your Combat SMG and aim for Juggernaut's head. Keep shooting until they die. It is best if you and your friend both shot at one Juggernaut, as it will kill them faster.

Then kill the remaining enemies, if any. Be careful of the enemies on the roof as well. After clearing all of them, hop into one of the choppers and deliver Agent 14 to the drop off point to successfully complete this setup mission.

The gap between two containers from where you can shoot the next two Juggernauts
Killing the Juggernauts through the gap
Final two Juggernauts

Prep 2 - Chernobog

In this mission, you need to go to a Merryweather Camp and steal a Chernobog missle launcher. It will be heavily guarded, so it's best if you go there in an Armored Kumara to clear the camp with full protection. You can also take a Buzzard or an Oppressor Mark II to clear them out. Once you've killed all the guards, the driver will get out of the Chernobog and run away. You can then hop into the Chernobog and bring it back to the facility.

Driver coming out of the Chernobog

On your way back, these mercenaries will keep on coming after you. If they are in front of you and you have enough speed then you can ram into them, which will instantly explode their vehicle. If they are behind you and shooting at you, then don't worry about it as the Chernobog has quite a lot of health and it won't get destroyed. Stay calm and drive it back to the facility.

Chernobog delivered to the facility

Setup 2 - Escort ULP

For this mission, you do not necessarily need to have a lot of snacks and armor but it would be good to have just in case, since you will be driving in the middle of a lot of enemies. One thing that is absolutely essential however is the Armored Kumara. You need to have an Armored Kumara for this mission to safely execute the first half of it.

Armored Kumara

First, you will need to go to the Paleto Bay Construction Yard and kill the security team. Since you will be inside your Armored Kumara, they won't be able to shoot at you. Stay inside the car and take out the whole security team.

After that hop into the Chernobog and drive to the landing site as instructed by the game. Once you reach the landing site, you will notice that ULP is being chased by some attack choppers. You need to go into stationary mode while inside the Chernobog and take out the enemy choppers chasing ULP.

If your friend is driving the Chernobog then you will be the missile controller and if you are driving then your friend. So, make sure you guys communicate well to stop the vehicle and drive it on time.

Killing the security team at the construction site

You need to keep driving with ULP and whenever there are enemy choppers gathering around him, take them out. Do not worry a lot about the choppers on you. Your Chernobog will be able to handle quite a lot of damage but ULP's helicopter won't. There is a health bar at the bottom right corner indicating ULP's helicopter health. Do not let it go down.

Make sure you always destroy the choppers heading towards ULP and then the one's on you. You might as well ignore it if there is only one chopper attacking you in your Chernobog as it won't do a lot of damage. Keep driving with ULP and stay close to him. As soon as you see some choppers heading towards ULP, take them out. Remember to communicate with your friend and tell him when to stop or go.

Destroying enemy helicopters

After a while ULP will be in the clear and the enemies will stop spawning. Keep following ULP and you will automatically get a "Setup Passed" message.

Prep 3 - Flight Path

In this prep mission you need to go to a certain location and identify a target. Lester will send a picture of the target to your messages. Either way he will be marked so you don't have to worry about it.

When you reach the location, the target will leave the area and walk away. Follow the target until he reaches a secluded area and then take him out using a suppressed weapon from a distance.

Target in a quite place

After taking him out, get his briefcase and bring it back to the facility to complete this prep mission.

Setup 3 - Barrage

For this mission, you are required to take down a Cargobob transporting an ATV. You need to intercept the convoy and get the ATV. After getting the ATV head to Sandy Shores Airfield and destroy the operation there. After the destruction of the operation you need to deliver the ATV to the drop off point.

Another very important aspect of this mission is to make sure you take an Armored Kumara as your choice of vehicle when going to the Observatory, as this will setthe Kumara as your personal vehicle (see further below). Also, ensure you are fully stocked up on snacks and armor, you're going to need them.

First you will need to go to the Observatory and destroy the Cargobob and the guarding helicopters. You will be given a sniper rifle with explosive ammunitio so two shots to the guarding helicopters would take them down. As for the Cargobob, you will be able to see the health of the Cargobob at the bottom right corner of the screen. Wait for it to get closer to you before finally taking it down. This will save you the hassle of going to the ATV resting far away from you. It will instead fall closer to you.

Cargobob carrying the ATV guarded by helicopters

Once you get the ATV, you are going to be swarmed by enemies from all angles. Quickly get into the ATV and whoever is using the turret on the ATV, make sure they use the front mounted gun as it doesn't restrict where to aim, as opposed to the one mounted at the back.

Rush to the Sandy Shores Airfield in your ATV and try to destroy the incoming enemies from a distance because as soon as they are beside you, they do a lot of damage. When you are driving to the airfield there will be a lot of road blocks as well. The best way to pass them safely is to open up your inventory menu and hover over the snacks/armour as you are driving through them. If you get stuck and the enemies shoot at you, you can quickly eat the snacks or put on the armor to avoid death.

Enemies already spawning after getting into the ATV
Armor menu opened up while passing through the road block

Once you reach the airfield, this is where your personal vehicle the Armored Kumara comes in. You need to quickly destroy the plane which is about to take off first, and at the same time request your personal vehicle from the interaction menu. Your Armored Kumara will be delivered. The reason for this is because the enemies in this mission are outrageously strong and they can easily kill you. When you have the Kumara you and your friend can hop into it and kill everyone at the airfield. After eliminating everyone head back inside the ATV and continue forward.

Airplane destroyed at the Sandy Shores Airfield
Killing everyone at the airfield after requesting the Armored Kumara

After the airfield there is another major road block ahead, where you can easily die. In order to avoid it, simply take a left and drive off road. Keep driving until you pass the road block and also remember to keep your inventory menu opened up. Either snacks/armour depending on what's low for you. Once you've passed this road block, you can safely deliver the ATV to the drop off without any more enemies spawning.

Going off-road to avoid the last road block on the right
ATV successfully delivered

Prep 4 - Test Site Intel

In this mission, you will be asked to go to a house and retrieve information about where the Khanjali tank is being tested at. The house location varies every time, however the guards and the approach are always the same. You can go in blasting which will cause the cops to be alerted, but you can easily lose them by calling Lester. Or you can eliminate the guards silently and then head inside the house. Use a suppressed sniper rifle to kill the guards and then when you're inside use a suppressed pistol to kill the guards silently. Sometimes, other guards who are around will be alerted if you kill a guard too close to another one.

Guard outside the house

You don't need to kill all the guards, you just need to kill the guards who are in your way and the ones you absolutely have to kill. You're looking for a green colored lockbox inside which you will find a laptop containing information about the location of the test site of the Khanjali stealth tank. Walk in stealth mode when you're inside the house or else you will alert the guards inside. Once you get the laptop, leave the house and bring it back to the facility which will conclude this prep mission.

First guard inside the house
Lockbox containing the laptop

Setup 4 - Khanjali

For this mission you should be stocked up on snacks and armor just in case. You probably won't need them since you will be taking an Armored Kumara to the test site though. Hop into the Armored Kumara and head to the test site which is an aircraft scrapyard. When you reach the location, destroy some equipment and steal the Khanjali tank.

First you need to kill the enemies surrounding the warehouse, then drive your car inside the warehouse and kill the enemies there too. When you see a good opening and no enemies around, leave the car and switch to your RPG. Use the RPG to destroy the equipment inside, just make sure you stand far away and don't accidentally blow yourself up. If you want to be extra careful, you can use sticky bombs.

Moving on, after destroying the equipment you need to head back inside your Armored Kumara and continue driving forward towards the tank. Keep killing the guards and moving forward.

Killing the enemies at the aircraft scrapyard (test site)
Destroying equipment

Once you get the tank, drive it to the drop off point. You are going to face a lot of resistance while driving the tank to the drop off point. There will be attack helicopters, other tanks and soldiers. You can use the rail gun on the Khanjali tank to easily take out all of these guys. Your friend will also have control of the machine gun mounted on the tank. When you get close to the drop off point, the enemies will eventually stop spawning and you can easily deliver the tank, successfully completing this setup mission.

Killing more enemies moving towards the Khanjali tank
Khanjali tank at the test site
Khanjali delivered to the drop off point

Prep 5 - Onboard Computer

You need to shoot down a prototype Hydra in this mission and need to get either a Buzzard, which is easily accessible through CEO Vehicles in the interaction menu, or you can use an Oppressor Mark II if you have one. We also recommend that you buy a couple of rebreathers, as you will need to get the module by diving underwater after shooting down the Hydra.

Get into either your Buzzard or Oppressor and head towards the Hydra. When you get closer to the Hydra, you wont be able to lock on to it and will need to manually get closer and shoot it down. Two missile shots should do the trick.

Hydra prototype

Once you've shot it down twice the Hydra will crash underwater. Go to your interaction menu and put on rebreathers from the gears section. After that, head underwater and recover the module from the cockpit of the crashed Hydra. Once you recover the module, deliver it back to the facility.

Crashed hydra underwater

Setup 5 - Air Defenses

In this setup mission you and your team mate need to go to Sandy Shores Airfield and pilot the Volatol over Mount Chilliad, in order to destroy the SAM turrets.

If you're the one piloting the aircraft, then as you are flying over the SAM turrets, hold down the bomb dropping button and a series of bombs should drop as you pass over the turret, which will destroy it. At the same time, your friend who is in the plane with you needs to use the mounted machine gun to destroy the turrets as well.

There are a total of 12 SAM turrets you need to destroy and you will also face some resistance as enemy choppers will try to defend the SAM turrets by attacking you, but your friend can easily take care of them using the mounted machine gun.

Destroy all the turrets and return back to the Sandy Shores Airfield to complete this mission successfully.

Volatol

Act 3 Finale - The Doomsday Scenario

This finale is the most difficult out of all the other missions you've done so far in this Act. It's also much harder than the finales of Act 1 and 2. Be sure to buy the maximum number of snacks and armor you can.

First, you and your team mates need to go to Grapeseed and choose either the Khanjali tank or the ATV. We recommend you choose the Khanjali, since it will provide more protection when going inside. It is slower to ride in, but you will thank us when you get inside the base.

Driving the Khanjali tank to the tunnel entrance

After getting the Khanjali drive to the tunnel entrance, once you get inside the tunnel you will need to fight your way to the end of it. Since you're inside of a tank nothing will cause you harm. Keep destroying the blockages and reach the end of the tunnel.

When you reach the end, do not get out of the tank just yet as some good old AI Juggernauts will spawn, and not just one ,but four of them! You can use the rail gun on your tank to kill them instantly. After killing the Juggernauts, proceed forward through the base. You will come across many enemies, take cover by the wall and take them out before proceeding forward.

Making our way to the end of the tunnel
Killing the Juggernauts using the rail gun on the Khanjali tank
Killing the enemies in the next area after killing the Juggernauts

As you reach a little open doorway, another AI Juggernaut will spawn. So before passing through that opening, switch to your mini-gun and pre-aim as you move forward. As soon as you see the Juggernaut, start shooting. Take it out, as well as the rest of the guys in that passage way, using your mini-gun.

As you move forward, you will come across an intersection where you can go either right or left. First go right, but not all the way. Just half way through the passage and on the right hand side you will see a small room with the first supply box. Destroy it by shooting at it. After destroying the first supply box go back to the intersection and take the left.

Another Juggernaut spawning when moving through the tunnel
Intersection to go either right or left
First supply box

Go straight through this passage and keep an eye ahead of you, as some guys might come at you. Once again to your right you will see another small room with a supply box. Destroy this box and continue forward.

As you reach the end of this passage you will turn right and come across a lot more guys to kill, all along the passage. Keep eliminating them and moving forward. At the very end there is another supply box, but you don't have to go all the way to the end to destroy it, you can simply shoot from a fair distance and you will see an explosion indicating the destruction of the supply box.

Second supply box
Killing more guys along the passage at the end
Third supply box at the end of the passage. Just aim in this general area (circled in red) and shoot

Now keep moving forward and you will see a wide opening to your right, this opening will lead you to the hangars. When you go through the wide opening, immediately take a right towards the hangars where you will find two more boxes on either side of the room by the planes (right and left side). Remember there are many enemies spawning here, so clear them before you proceed towards the hangars and the boxes.

Opening to the right along the passage
Fourth supply box in the hangar by the plane to the right
Fifth supply box in the hangar by the plane on the left side

After getting the supply boxes at the hanger, move forward to the next area through the hangars. You will see an opening on the right hand side, at the end of the hangar room. As you go through the opening you will come across two guys. Kill them and move forward where you will find another one in cover by the boxes to your right and a couple more ahead of you.

Be careful here as there are two Juggernauts at the end of this passage way. Take cover by the boxes to your left and then use your mini-gun to take out the Juggernauts. Remember you can take them out standing at the edge of the boxes and shooting at them - you can shoot through the boxes when standing by the edge. Move forward and clear out the remaining enemies. You will also find two on the platform above to your left.

Moving forward through the tunnel killing two guys in the passage
Killing one of the Juggernauts at the end of the tunnel

Proceed towards the control center and you will go through a passage way. Here, you will once again encounter 3-4 guys after which a cut scene will play. Upon the completion of the cut scene, you will be in the server area/control center and see red double door in front of you.

Do not rush out through that door just yet as there are a number of guys outside waiting for you. Shoot at the door to partially open it up and you will notice at least three guys on the ground floor and one straight ahead of you, up on the platform. Take them out and then move out.

As you move outside, you will see three more on your right side and three more to your left. You will also see one more guy on the upper floor to your right. After taking them out go upstairs from right side and just rush to the first server.

Be sure to ask your friend to stay with you at all times. As soon as you get to the first server start hacking. When you are hacking, the enemies will not shoot at you. However, as soon as you're done hacking the server, they will instantly start shooting at you.

Enemies on the ground floor just outside the double door
One guy straight ahead upstairs
Three enemies to the right after going through the double doors
One of the three guys on the left side

Ask your friend to take cover at the end of the server and keep killing as many enemies as possible. He should clear as many as possible in order to ensure that you are not swarmed with enemy fire. As soon as you're done hacking the first server, check if the coast is clear then rush to the second server. If it is not clear then you also need to get into cover with your friend and hack the server. The hacking procedure is really simple. You just need to break the blue colored nodes by passing the signal through them, while avoiding the red nodes. If you hit the red node multiple times then you will fail the hack and have to restart.

Hacking the terminal
Hacking interface

After hacking all four servers, the enemies will stop spawning and you just need to kill the remaining ones. After killing the remaining enemies, head upstairs and take control of the Orbital Cannon to destroy the four mobile cloud servers. Then go downstairs and make your way to the Silo.

The way to the silo is once again filled with a number of enemies. You need to take your time, kill them and then move forward. Do not rush in. It's a narrow passage and it is easy for you to get trapped and die. Keep going forward until you reach the end where a cut scene will play. In it, Avon will escape the base using his jet pack. You and your friend will need to get on the jet pack and follow Avon and kill him.

Orbital cannon control panel
Orbital cannon interface
Narrow passage leading to the Silo

Remember, when you are chasing Avon, you need to focus solely on him. There will be a number of enemy choppers defending Avon and attacking you. Your jet pack will have homing missiles and you can lock on to the targets. Destroy any nearby choppers and then try to focus on Avon, the moment Avon dies, all of the other choppers will go away as well.

After killing Avon, you and your friend need to make your way to the Observatory where one final cut scene will play, concluding our Doomsday Scenario.

Avon escaping using his jet pack
Avon (circled in red) killed using the homing missile on jet pack
Moment from the final cut scene
Hassan Sajid

I've been playing games ever since I was a kid. I started off with the PSX and PS2 and now finally have a PC. My first GTA game was Vice City and ever since that I have been hooked on the GTA Series. Ultimately, GTA San Andreas is my favorite! Along with GTA games, I am a huge fan of the Call Of Duty series, as well as Assassins Creed and the recently released Red Dead Redemption 2. Find me on LinkedIn.