Mauer der Toten Easter Egg Guide is built around Klaus, the CRBR-S Wonder Weapon and a hidden Berlin laboratory that eventually leads to Valentina. It is one of Black Ops Cold War’s more involved Main Quests because several steps have their own setup requirements, including fully upgrading Klaus, building his Hacking Helm, charging three canisters and completing two timed uranium runs.
This Mauer der Toten Easter Egg Guide keeps the quest in the safest order for solo or co-op play. The biggest advice is simple: do as much setup as possible before triggering the uranium timer, and do not place the second Cleansed Rock into the Secret Lab pedestal until you are ready to fight Valentina.
Mauer der Toten Easter Egg Guide: Quick Route
| Stage | Objective |
|---|---|
| Setup | Turn on power, activate Pack-a-Punch and build Klaus. |
| CRBR-S | Obtain the CRBR-S and secure the Blazer mod. |
| Klaus upgrade | Find the Microwave Dish and two Cosmetic Disks, then complete Klaus defenses. |
| Hacking Helm | Collect Antenna, Transistor and Electronic Boards. |
| Secret Lab | Use Klaus and CRBR-S Blazer to enter the lab, then charge three canisters. |
| Train | Switch the tracks and use Klaus to stop the train for the Keycard and Warhead. |
| Uranium | Complete two timed HVT Megaton uranium sequences. |
| Boss | Insert the second Cleansed Rock and defeat Valentina. |
Turn on Power and Pack-a-Punch
The Mauer der Toten Easter Egg Guide starts by opening the route through the Berlin streets and underground areas until you can restore power. You need two Tempest fuses for the underground power switch. Once the power is active, head toward Checkpoint Charlie and clear the Pack-a-Punch encounter to unlock the machine.
Use these early rounds to build armor and reach the perk setup you want. The quest has several defense and escort-style sections, so survivability matters more than trying to complete every step at the lowest possible round.
Activate Klaus
Klaus is central to the Mauer der Toten Easter Egg Guide. You need the Battery dropped by the first Krasny Soldat, which normally appears from round 10, plus the robot hands found in Hotel Room 305 after using Brain Rot on a zombie to open the boarded room.
Install the parts on Klaus in the Safe House. Once active, Klaus can be directed with the remote and will perform interactions that the player cannot, including opening quest containers and stopping the subway train.
Get the CRBR-S
You also need the CRBR-S for the Mauer der Toten Easter Egg Guide. The weapon can come from its free safe quest, Trials or the Mystery Box. The quest route is reliable and worth learning because later stages specifically require the CRBR-S Blazer conversion.
Keep killing zombies with the CRBR-S until the required Mod Kits begin dropping. The Blazer is the important one for the hidden lab because its focused beam melts the metal door after Klaus breaks through the brick wall.
Fully Upgrade Klaus
The next Mauer der Toten Easter Egg Guide stage requires the Microwave Dish and two Cosmetic Disks. Search the debris piles in the kill zones beside Pack-a-Punch for the Microwave Dish. Use the blacklight to inspect the possible Klaus-marked boxes around the map and order Klaus to smash the two boxes that contain the disks.
Take the parts to the Garment Factory Upgrade Station. Build enough Klaus kills to turn the station display green, direct him into it and defend the machine. Repeat the required upgrade process until Klaus is fully upgraded.
Build Klaus’s Hacking Helm
The Hacking Helm is another mandatory part of the Mauer der Toten Easter Egg Guide. Shoot the rooftop antenna with the Wonder Weapon for the Antenna piece, shoot the radios in the Electronics Store until the Transistor drops, and shoot the small box at the Ghost Station ticket booth for the Electronic Boards.
Return to Klaus in the Safe House and install the three components. Klaus now has the equipment needed for later quest interactions.
Mauer der Toten Easter Egg Guide: Open the Secret Lab
Lead Klaus into Sewer Access for the next Mauer der Toten Easter Egg Guide step and direct him toward the blank brick wall. He breaks it open, revealing a metal door. Equip the CRBR-S Blazer and fire at the door until it melts.
Survive inside the Secret Lab until the red shields drop, then take the three canisters. Place them into the large green harvester units around the map. Return to the lab for Tempest lures, place a lure near each harvester and kill the spawned Tempests close enough to charge the canister. Return all three glowing canisters to the lab pedestal.
Stop the Train
Once the canisters are charged, the Mauer der Toten Easter Egg Guide sends you to the Switch Control Room. Change the tracks, summon Klaus and direct him onto the correct Ghost Station track. When the train arrives, Klaus stops it.
Board the train quickly and take the Keycard from the body and the Warhead from the crate. Bring the Warhead to the Secret Lab and use the Keycard on the Safe Room computer until the Disruptor Satellite option appears.
Mauer der Toten Easter Egg Guide: Complete the Two Uranium Runs
The uranium stage is the most dangerous timed part of the Mauer der Toten Easter Egg Guide. Use the West Berlin military tent computer to activate the Disruptor Satellite. Kill the HVT Megaton and collect the two Uranium Rocks. The five-minute countdown starts when the Megaton dies.
Craft both rocks into Uranium Devices at the tent workbench. Take one device to each end of the rooftop zipline and attach them so they collide, creating a Cleansed Rock on the street below. Return it to the lab. Advance the round and repeat the sequence using the East Berlin tent for the second Cleansed Rock.
Do not insert the second Cleansed Rock immediately. Drop it safely near the pedestal and finish every upgrade first, because inserting it starts the Valentina fight.
Defeat Valentina
Valentina is the final fight in the Mauer der Toten Easter Egg Guide. Break her blue shield, then damage her health while watching for her fire attacks, healing phase and screen-distortion attack. When she summons floating zombies, kill them quickly or she can drain them to recover health.
The fight moves through several Berlin locations before returning to the Secret Lab. Use the short transitions to refill ammunition and repair armor. Once Valentina falls in the final phase, interact with her body and complete the final Klaus story sequence to finish the Main Quest.
For the official map background and Dark Aether story context, see Call of Duty’s official Mauer der Toten guide.
