The Black Ops 4 Zombies Blood of the Dead Easter egg is a remake of Mob of the Dead from Black Ops 2, so it may seem familiar to any zombies veterans out there. This map has the Primis crew on board but many moons ago, so Dempsey, Belinski, Masaki, and Richtofen are much younger in this Black Ops 4 Zombies map than we've seen before. Get your pen and paper out though because there are a lot of steps to complete in the Black Ops 4 Zombies Blood of the Dead Easter egg.
As for the Easter egg itself and all the things to unlock, there is a lot to do. From turning on the power and unlocking Pack A Punch, to obtaining the three different wonder weapons and getting started on the main steps, Blood of the Dead is considered to be the most difficult of the three base maps in Black Ops 4. Without further ado, let’s get started with what you need to do first.
- Black Ops 4 Zombies Voyage of Despair Easter eggs
- Black Ops 4 Zombies IX Easter eggs
- Black Ops 4 Blackout Character Missions - unlock all Zombies characters
How to turn on the power
As soon as you spawn, your first goal is to turn on the power. Unlike Classified which just has one power switch, to completely turn on the power in Blood of the Dead you need to find two power switches.
From spawn, head through Model Industries and West Grounds to the Power House. The power switch is lit up in the corner of the room, next to the words “Lights Out” scribbled on the wall in blood.
This will unlock the Catwalk and the path through the Recreation Yard. Head into the main Alcatraz prison, through D Block and down C-D Street to the Cell Block 3rd Floor. Take the path down Michigan Avenue and into the Citadel, then go all the way down the spiral Citadel Tunnels. At the other end, you’ll exit to China Alley. Head in to Building 64 and the second power switch is at the very back of the building.
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Building the Spectral Shield
Now you’ve turned on the power, you want to focus on getting the Spectral Shield as it’s a key item that you’ll use throughout the entire map. As per usual with Treyarch’s Zombies maps, you need to find three parts to craft it, each with different spawn locations. Here’s where you can find the Spectral Shield parts:
- At the very bottom of the Citadel Tunnels is the doorway to China Alley. The first part can spawn to the right of the doorway.
- It can also spawn through the doorway, at the top of the staircase in Citadel Tunnels.
- The third spawn location is next to the locked elevator cage at the very top of the Citadel Tunnels.
- Part two also has three spawn points. The first is on the upper level of Times Square, on the wall next to the Auger DMR wall-buy. It glows so it’s hard to miss.
- Check the Library next, as it can spawn inside a box.
- Head to Michigan Avenue if you haven’t found it at the previous two locations because it may be underneath the Michigan sign.
- The final piece is the Warden’s Key and to get this, you need to slay the Warden himself. He spawns as soon as you turn on both power switches - kill him and grab the key from his corpse.
Next, you actually need to build the Spectral Shield. Head to one of two workbenches, either by the Docks or on the Cell Block Third Floor, and interact with it to build the shield.
Along with defending you from zombie hits, the Spectral Shield also has a secondary attack with the Warden’s Key. You need to drain the souls from zombies by using your secondary attack to build up charges for the Spirit Blast. Once you’ve got a few charges in there, you’re going to want to head to the roof of the prison to unlock Pack A Punch.
Upgrading the Spectral Shield to the Attuned Spectral Shield
This step is completely optional but it’s fairly simple to do and it gives your Spectral Shield more durability, along with an extra Spirit Blast charge. To upgrade it, you need to have the Hell’s Retriever and the Spectral Shield already, so read on to the Hell’s Retriever stage if you haven’t already.
Find the Mystery Box and use it until you get a padlock. When you do, equip your Spectral Shield and drain the life from the padlock with your key. When the lock turns blue, throw the Hell’s Retriever at it and your shield will be upgraded to the Attuned Spectral Shield. This is a great thing to do if you’ve got time to kill while teammates are upgrading weapons and doing their own steps for the Easter egg.
Unlocking Pack A Punch
You can see the Pack A Punch machine on the roof, but it’s not active. This is where your Spectral Shield charges come in - use the Spirit Blast attack on the power gauge to the side of the machine. This will activate the Pack A Punch machine for the rest of the game so you can upgrade your weapons for 5,000 points.
Obtaining the Hell’s Retriever
Now you want to think about getting all three wonder weapons on the map. The first is the Hell’s Retriever - a throwable tomahawk that replaces your usual equipment. As you can tell by the name, it also retrieves items, which is a crucial part to completing the map.
The first step you need to do to get the Hell’s Retriever is feed the three Cerberus heads on the map. You just need to kill enough zombies by them so they snatch them in their jaws and eat them. Here’s where you can find all three Cerberus heads:
- New Industries - New Industries is the first building you’ll explore. The Cerberus head spawns in the far corner.
- Cell Block Second Floor - In the Cell Blocks, head up the stairs and the next Cerberus head is in the middle of some railings.
- Eagle Plaza - The final one is on the side of the Warden’s Office in Eagle Plaza.
When all three Cerberus heads have been satiated, head to either the Warden’s House or the Showers. As long as you’ve turned on the power by this point, you’ll be able to use the fast travel. When you’re zooming through the lava-filled underground, look for the Hell’s Retriever floating on top of some rocks in the middle of the river. Pick it up as you go past and you’ll have it in your inventory.
Upgrading it to the Hell’s Redeemer
You can upgrade the Hell’s Retriever to the Hell’s Redeemer, though it isn’t required for the main Easter egg. To obtain the upgrade, you need to have the Spectral Shield already, so make sure you’ve done that in the steps mentioned above.
To upgrade it, you’re looking for a Spectral Image. It can be found in one of six locations:
- Through a cracked wall on the right side of the Citadel
- Through one of the windows with hanging corpses in the Citadel
- Above the entrance to the Warden’s Office in Eagle Plaza
- On the floor of Eagle Plaza, through a crack in the floor by a pipe protruding from the ground
- Look toward the Prison Entrance from the Recreation Yard and the image may spawn on some rocks
- On the same bridge in the Recreation Yard, look past the barbed wire and it can spawn behind it
To see it, you need to look through your Spectral Shield. When you find the Spectral Image, throw the Hell’s Retriever at it. This will temporarily remove the wonder weapon from your inventory. Now you need to wait till the next hell hound round, which will spawn a Spectral Dog. Equip your Spectral Shield again and start searching the entire map for the dog. The only clue you have is that you can see the paw prints it leaves through your shield vision.
When you find the Spectral Dog, shoot it with a Spirit Blast. You can now go and grab the Hell’s Redeemer from the same place you got the Hell’s Retriever - use the fast travel system and pick it up in the fiery tunnels.
Obtaining the Spoon
When you’ve got the Hell’s Retriever, you need to get the next wonder weapon. Despite it literally just being a spoon, unfortunately you won’t be eating any ice cream. The Spoon is a wonder weapon that replaces your melee weapon and is much more powerful than the knife… somehow.
To get the Spoon, head to the Warden’s Office. There’s three pillars - equip your Spectral Shield and you’ll see three spectral numbers. Take note of the numbers from the closest to furthest away. Make sure you’ve got a charge of your Spirit Blast and head to the bottom of the Citadel Tunnels where you’ll find a number pad. Shoot it with the Spirit Blast to activate it and input the three numbers you had in order.
Somehow, those three numbers will cause the enormous locked elevator to fall from where its hanging. It’ll land in the water below and the Spoon will float away. Make your way out to the Docks and there should be a power gauge down there. Shoot it with another Spirit Blast to activate the crane.
When the crane finishes moving, throw your Hell’s Retriever at the hanging net with a skeleton in. The Spoon will fall out of the net and land on the wooden crate by the edge of the dock. Pick it up and you’ve got a slightly better melee weapon that deals one-hit-kills for the earlier rounds.
Upgrading the Spoon to the Golden Spork
For this step, you need to have already obtained the Blundergat and upgraded it to either the Magmagat or the Acidgat. We’ve covered that in the next step below, so revisit this when you’ve done that.
If you want an incredibly powerful melee weapon that kills zombies in one hit until round 34, upgrade the Spoon to the Golden Spork. Make your way to the Infirmary and you’ll find an empty bathtub. Place the Spoon inside then go to the roof and keep the Pack A Punch machine company for a while.
With either the Magmagat or the Acidgat, you need to kill zombies on the roof. This will slowly start to fill the bathtub in the Infirmary up with blood. When the bathtub is eventually full, interact with it to drain all the blood away and you’ll see the Spoon has vanished.
Go down to the Recreation Yard and up the path to the Catwalk. Look to the enormous water tower on your right. There’s four hinges on the water tower that you can shoot off, although to hit them all you may need to look at the water tower from different angles. When all four have been broken off, the water tower will crumple. Go back to the Catwalk and throw your Hell’s Retriever at the base of the water tower and it should come flying back to your hands with the Golden Spork. Happy meleeing!
Obtaining the Blundergat
It’s possible to obtain the Blundergat via the Mystery Box, for the small price of 950 points. Of course, this isn’t reliable in any way so while you could get it on your first go, it may also take you 50 goes. Thankfully, you can also obtain the Blundergat for free.
With the Spectral Shield equipped, you need to search for and hunt down five Spectral Skulls. Thankfully, these all spawn in the same place each game so you don’t need to check multiple locations for each one:
- Opposite the Library entrance, inside a cell on C-D Street
- On the third wooden pole from the left in the water at the Docks
- To the right of the Pack A Punch machine on the Rooftop, a skull should be on a wooden crate
- On top of one of the poles in Eagle Plaza
- Part of the way up the metal staircase in West Grounds
To pick up all of the skulls, simply throw your Hell’s Retriever at them. We told you it comes in handy! After you’ve got them all, make your way to the Warden’s Office and you should be able to grab the Blundergat from on top of the desk.
Upgrading the Blundergat to the Magmagat
The Magmagat is the fiery version of the Blundergat. Firing it at the floor leaves behind molten puddles which damage any enemy that walks across them, meaning it’s a fantastic weapon for the later rounds. To upgrade it though, you need to jump through a few hoops.
As soon as you pick up the Blundergat off the desk, head to the fireplace and place the Blundergat in there. Kill zombies inside the Warden’s House and they will drop essence. Walk over the essence to pick it up and the three skulls above the fireplace will start to fill up. When all three are flaming blue, interact with them to deposit the essence and the Blundergat will come out of the fireplace as the Tempered Blundergat.
As soon as you pick it up, a time trial will start. Make sure you do not fire the weapon and use your other gun instead for any zombies you kill. You need to race against time and interact with six flaming blue barrels in this order:
- Eagle Plaza
- Michigan Avenue
- Times Square
- Recreation Yard
- West Grounds
- New Industries
When you reach New Industries and interact with the barrel there, interact with the compactor machine by the side and two spectral ghosts will appear. Let them do their thing with the machine and it will give you the Magmagat in return. Pack A Punch it for the Magmus Operandi, an incredibly powerful gun that will kill almost every enemy in just a few hits.
Note that if anyone else wants to upgrade their Blundergat to the Magmagat from this point onwards, they just need to interact with the compactor in New Industries. They don’t have to do the time trial themselves.
Upgrading the Blundergat to the Acidgat
If you’d prefer the poison version of the weapon known as the Acidgat, you need to search for some more parts. Again, these don’t actually have random spawn locations so you should be able to pick them all up from the same place every game:
- The first part is in the Transverse Tunnel, on the floor by the right-hand wall near a wall-buy.
- Next, head to Sally Port. In one of the rooms is a table with a skull and a morse code machine. Remember this morse code machine because you’ll need it later down the line but for now, grab the third object on the table which is the second part for the Acidgat.
- The Infirmary is where you’ll find the third part. In the corner of the room, near the path to the Rooftop is a cabinet. Interact with it and the Warden’s Key will open it.
With all three parts, head to a workbench to build the Acidgat - either on the Docks or Cell Block Third Floor. If you’ve already got the Magmagat you can exchange it for the Acidgat. Pack A Punching it will create the Vitriolic Withering which, as you’d expect, is very powerful.
How to earn free Monkey Bombs
The final thing you’re going to want to do before cracking on with the main Easter egg is obtain Monkey Bombs. Now these can come from the Mystery Box so if one of your team is lucky enough to have got them already, you can skip this step. If you haven’t got them so far though, then you’re going to want to follow these steps.
Note: Having Monkey Bombs will replace the Hell’s Retriever in your equipment slot so make sure someone else is grabbing these, as you’ll have to go underground to pick up the Hell’s Retriever again afterwards.
On the bottom floor of C-D Street, there is a zombie window that overlooks the very centre of the cell block. You’ll see it has caved in and of course, the area is inaccessible. Just before the crater is a stone statue of a Monkey Bomb. Ensure your specialist weapon has reached level two then kill as many zombies as you can with it by the monkey statue. The statue’s hat will begin to fill with zombie souls. When it turns red, shoot it and it will levitate then vanish. It’s popped off to Richtofen’s Laboratory - the room you spawn in. You can now pick up free Monkey Bombs from the teleporter pad by the typewriter.
Making a Brutus open the Warden’s Ritual Chamber
Now you’ve done everything above, it’s time to get started on the main Easter egg. By this point, you ideally want to be at about wave 10 or lower. This map becomes seriously tough, so getting everything done as early as possible is crucial.
First, you need to make a Brutus spawn. These are the big chaps with helmets that take one hell of a beating. Can’t find one? There’s a way to force a Brutus to spawn but you can only do this once per game, so ensure nobody else has already done this. Head to the number pad at the bottom of Citadel Tunnels, shoot it with a Spirit Blast to activate it, then enter “666”. This will spawn a Brutus right next to you.
Bring it over to the Warden’s House. At the top of the stairs is a completely blank wall on your left. Guess what? It’s hiding a secret door. With the Spoon or Golden Spork as your melee weapon, hit the wall and it should leave a mark. With the Brutus hot on your tail, throw down a Monkey Bomb in front of the wall. The Brutus should become attracted to the bait and he’ll perform a ground pound. If done correctly, the wall to the left will blast open, revealing a hidden Warden's Ritual Chamber.
Go inside and interact with the lever by the electric chair. Next, pick up the red stone on the table and head back down to Richtofen’s Laboratory.
Chasing the Spectral Bird
In Richtofen’s Laboratory, there’s a map on the wall. Interact with it to place the red stone on the map, then look on the floor for the Kronorium book and interact with that. A Spectral Bird will fly out of the window toward the main Alcatraz prison. This stage can get infuriating, as you essentially have to track down that bird.
It can spawn pretty much anywhere on the map. It can be in every single room, each with multiple spawn points. You can only see the bird through your Spectral Shield though, so every new room you go in, you’ll need to equip it and scan the room. The only help you get is that when you do equip your Spectral Shield and zoom in, the bird will make a noise that helps you pinpoint its location.
When you find the bird, shoot it with a Spirit Blast. It will fly off and you have to do the same thing again next round. And the round after that. The next time you look for the bird, it will now be an orb and you’ll be able to hear a man crying in the background. Before you shoot the orb, you need to do two things:
- Make sure there is nobody in the nearby vicinity. This step can bug out and break the Easter egg for the entire game. Get everyone else in your game to leave the area and kite zombies in different locations.
- Head down to the number pad at the bottom of the Citadel Tunnels and input “872”. It’s the same three numbers every game. When you input those numbers, a Zombie Blood Pack will spawn. Grab it and head back up to the orb.
Look at it quickly with your Spectral Shield and it should now be a bird again. As quickly as possible, throw your Hell’s Retriever at the bird instead of shooting it with the Spirit Blast. If you do it to slow, the bird will fly off and you’ll have to find it again next round. You’ll know you’ve done it correctly because the Kronorium will appear. Interact with it and you’ve completed the Spectral Bird step of the Blood of the Dead Easter egg.
The Five Trials
Like IX and Voyage of Despair, there’s a series of trials you have to complete in Blood of the Dead. You don’t get whisked away to an alternate reality for these though - you have to complete them with all the normal zombies swarming you. Some of these are incredibly tough and will require a lot of persistence, along with a couple of players kiting zombies elsewhere on the map to ease the burden on the players completing the objectives.
To kick off the trials, head back to the Warden's Ritual Chamber in the Warden’s House. Interact with the electric chair to place the Kronorium and the pages will start flipping non-stop. Interact with it again, then equip your Spectral Shield. You’ll see three numbers - take a mental note of them. You’re going back down to the number pad in the Citadel Tunnels to input them.
Doing this will cause the lighthouse beam to move and shine at a specific location. Each location represents a challenge. Before we get on to the specific locations and challenges, whenever you approach the location the beam is pointing at, make sure you’re firing a Spirit Blast at the red portal to start the challenge. After you complete each one, you also need to revisit the Warden's Ritual Chamber and take down three more numbers from the Kronorium, then input them each time into the number pad.
The order you receive these challenges is completely random and if you fail it, when you get more numbers and input them again, you could either get the same challenge again or a completely different one. Without further ado, here are the five Blood of the Dead trials.
One location the lighthouse beam can point to is the Showers. When you get there and you’ve shot a Spirit Blast at the red portal, you’ll be able to see a Spectral Zombie playing the banjo. This is one of the stranger trials without a doubt. He’ll play the banjo for a few moments before holding it out for you. Interact with the Spectral Zombie to take the banjo off his hands and carry it on your back. Blue circles will appear on the ground. Stand in them and kill zombies while the banjo is on your back to collect zombie souls. Note that if you’re outside of the circles with the banjo on, you’ll start to slowly take damage.
Do this a few times and when you give the Spectral Zombie his banjo back, he’ll vanish and leave behind a red stone for you, much like the one you’ve already placed on the map in Richtofen’s Laboratory. Head back to the Warden's Ritual Chamber to get more numbers and start the second trial.
Head to the Docks and Spirit Blast the portal, then make your way over to the Warden’s House. There’s a lamp flashing in the house which is emitting morse code. Take note of the code until it starts to repeat itself, then head through the Warden’s Office into Sally Port, the room opened by the Warden’s Key which contains the Acidgat part.
You need to enter the morse code in the machine on the table that we mentioned earlier. Dots are a quick press of the button, while dashes are longer holds (approximately three seconds). If you get it wrong, you’ll heard the Warden laugh and you can start over. You’ll know when you’ve done it correctly because your character will confirm it and you won’t be able to interact with the machine anymore.
Next, head up to the Cell Block Third Floor and to the Gondola at the very end. Look off the edge of the Gondola into the ocean with your Spectral Shield and you should be able to see a Spectral Boat. Your character will comment on the boat, even if it’s quite tricky to make out.
Once you’ve done that, head to the Infirmary and look for a hospital bed with a skeleton on. Kill a zombie next to it and a Spectral Zombie should spawn when looking through your Spectral Shield. Spirit Blast it to make it visible to the naked eye then kill a few more zombies and the Spectral Zombie should start following you. Your goal is to escort the Spectral Zombie all the way to the Gondola, then ride the Gondola down to the Docks. Approach the portal and the Spectral Zombie will disappear, leaving another red stone in its wake. Pick it up and get ready for the next challenge.
Once you’ve been back to the Warden's Ritual Chamber and entered four more numbers in the number pad, if the lighthouse beam is aiming at the Power House by spawn, head there and spirit blast the portal. You then want to make your way to the opposite side of the map, to Building 64, where the second power switch can be found.
Notice the sparking generator in the corner of the room. Interact with it and the lights in the room will shut down. This will trigger a game of Simon Says. There’s five rounds in total: for the first round, one machine will light up. When the light goes out, interact with it and the second round will start. Two machines will light up; interact with them in order and so on until you’ve completed all five rounds of Simon Says.
When all five rounds are finished, lights will remain turned on above three of the machines for approximately five seconds. Each one of these will have a symbol attached to the bottom on some paper. This cheat sheet from the /r/CODZombies subreddit is a handy way to remember which symbols you got as you just have to remember the corresponding numbers rather than draw the symbols themselves.
Before you leave and move on to the next step of this challenge, approach the shelf in the middle of the room with a skull and six candles on. There’s also a punch card - pick this up because you’ll need it to move on.
Head to Model Industries - the room above Richtofen’s Laboratory in the West Grounds and insert the punch card into the machine here. This will turn on monitors in the room, each displaying the six symbols from Building 64 - three of which you should have remembered on the cheat sheet as yours. Find the monitors displaying your symbols, then pay attention to the next symbol those monitors show. They will correspond to one of the symbols on the second part of the aforementioned cheat sheet. Remember the number for each of those symbols, then head on down to the Power House where you initially started this challenge.
Equip your Spectral Shield and look toward the machine surrounding the first power switch you interacted with at the very start of the game. There’s another Spectral Zombie slowly meandering between the levers attached to each of the machines, pulling each one in turn. Below each lever is a symbol. Find the right levers for your three new symbols you’ve got noted down, then as the Spectral Zombie approaches the lever for your symbol, shoot him with your Spirit Blast. He will become visible to the naked eye and turn the lever, before turning spectral again. Do this for all three of your symbols and after the Spectral Zombie pulls the third lever, he will disappear and drop another red stone on the floor. Pick it up and head back to the Warden's Ritual Chamber to grab your next challenge.
This challenge is without a doubt the toughest one to complete. You and your teammates want to have as many Spirit Blast charges in your Spectral Shield as possible, because you’ll be using them a lot. Head to New Industries near spawn and fire a Spirit Blast at the red portal to start the challenge.
From there, cross the Recreation Yard and go into the Library to the right of the Cell Block Entrance. Kill a zombie and another Spectral Zombie will spawn, one that you can only see through your Spectral Shield vision. Fire a Spirit Blast at it to make him visible then start using your key to drain his health as much as possible. Your goal is to turn this Spectral Zombie completely red before he makes it to the New Industries building.
The reason this challenge is so tough is because this guy has a lot of health. You also need to constantly Spirit Blast him to make him visible, which means having to find and kill zombies with the key takes away precious seconds you could be draining his health away. There’s also the fact that you’re likely to be in round 15+ by this point so the game starts to get trickier and this challenge can be infuriating.
One trick we know about is to stand in front of the Spectral Zombie so he can’t actually get past you while you drain his health. It’s easiest done on corners and may be necessary to get him weak enough before he reaches New Industries.
When he does reach the New Industries door, if you’ve got him bright red, head inside and activate the trap in the very middle of the room. When he passes through, the trap should finish him off and a red stone will drop in the middle. Pick that up and get ready for the final challenge, which is another escort mission.
When you’ve got the lighthouse pointing toward Michigan Avenue, head to the end where the entrance to the Citadel Tunnels is and Spirit Blast the red portal for the final time. Get all players to move to the Cafeteria then kill a zombie inside. Another Spectral Zombie will spawn, visible only through your Spectral Shield. Spirit Blast him and he will start his journey.
You literally just have to defend him, the opposite of the New Industries trial. Kill all the zombies before they can damage him on his route. You’ll notice a lot of other Spectral Zombies cheering him on from inside their cells which is a neat touch. More zombies than usual will spawn during this round which can make it difficult, but as long as you take advantage of a fully upgraded specialist weapon and the Magmus Operandi or Vitriolic Withering, you should be able to protect your ghostly friend.
Eventually, he’ll make it to the red portal at the end of Michigan Avenue and drop another red stone. Pick it up and finally, you’ll have completed all of the five trials. Do note that if you failed any of the challenges at any point, you will only have to re-do that one again. Any already completed ones up to that point will stay completed.
Escaping the Warden’s clutches
Now you’ve done all five trials, prepare yourself for the final boss fight. Make sure your specialist weapon is fully upgraded, you’ve got a Pack A Punched and upgraded Magmagat or Acidgat, and you’ve bought all the perks. Head down to Richtofen’s Laboratory and interact with the map to place all five red stones on the map.
Make your way back to the Warden’s Ritual Chamber and interact with the corpse in the electric chair. This will commence a cutscene where the Warden will knock you out and you’ll be teleported to the cells. At the end of the cutscene, the Spectral Bird will make a fleeting appearance, freeing you from the cells. Grab another Spectral Shield from the workbench right next to you then look round the corner and you’ll see the Spectral Bird floating in a doorway. Interact with the sack beneath the bird and you’ll receive all of your weapons and equipment back, since the Warden took them off you.
Follow the bird out of Alcatraz and kill the Warden that stands in front of you. Keep following the bird through the Recreation Yard and back to the West Grounds. In front of you, the Warden will reappear again and go through a mini-animation before some more Spectral Zombies appear and start fighting the now-oversized Warden. When they leave, pick up the final red stone that appears beneath them. Go into Richtofen’s Laboratory, put the stone on the map and the final boss fight will be ready.
Final boss fight
Head upstairs and have all players stand by the big sliding door. You’ll then be able to interact with the door and proceed into the boss fight against the Warden. The Spectral Zombies are still clinging on to the Warden but eventually, he’ll throw them off. Take note of the big machine in the middle, as you need to focus on it during the fight.
At first, focus your attention on killing zombies and hell hounds with your Spectral Shield key to get some Spirit Blast charges. When you’ve cleared enough of the smaller enemies, a Max Ammo power-up will spawn along with a Carpenter. The Warden will jump onto a rock and create a red zone around himself. Head inside the zone and shoot at the floating red orbs he creates. Do not shoot them with the Blundergat or any version of that weapon because it will not deal any damage to them. Instead, use one of your other Pack A Punched weapons to destroy the orbs.
When all the orbs are destroyed, use a Spirit Blast on the Warden, then use a Spirit Blast on the white orb sat atop the machine in the middle of the arena you’re fighting in. Do this three times in total; kill the smaller zombies, destroy the orbs then Spirit Blast the Warden and the machine orb. The only difference is that there will be some symbols on the floor that will deal damage to you if you step inside them, along with some toxic gas. When you’ve done it for the third time, you need whoever is playing as Edward Richtofen to interact with the machine in the middle. Note: if you’re playing with less than four people and Richtofen isn’t in your game, a bot will spawn in.
Richtofen will go back down to Richtofen’s Laboratory while the other players in the game are still on the surface defending themselves from more zombies. Richtofen will now have a fiery gem though. He needs to make his way back up the stairs, interact with the door again to rejoin the others, then interact with the machine in the very middle of the arena. This will cause another cutscene to play, signalling the end of the Blood of the Dead map.
As a side note, Treyarch has been making minor adjustments to Easter egg steps on the Black Ops 4 Zombies maps, in order to fix bugs and make things have more logic. One example of this is the Golden Spork step - when the game launched, you didn’t have to shoot the hinges off of the water tower, you could just grab the Golden Spork with the Hell’s Retriever from the bottom of the normal water tower. They fixed that step to make it seem more logical. If anything here isn’t correct in the future, do let us know.
If you're done with Zombies after all of that, why not check out our Black Ops 4 Blackout tips?