18 November 2025

How to Solve the Serum Puzzle in BO7 Zombies

By newsgame

Collecting all 6 Serum parts in Ashes of the Damned can be overwhelming, and so can the final Serum puzzle that players need to solve if they want to progress through the Ashes of the Damned easter egg or get the DG-2 Turret upgrade for Ol’ Tessie. Luckily for you, we’ve provided a detailed and step-by-step guide on how to get all 6 Serum parts in Ashes of the Damned, and better yet, how you can easily solve the Serum puzzle in Black Ops 7 Zombies to ensure a fast completion of the easter egg.

All Serum Parts Locations in Ashes of the Damned

Serum Part #1 – Powder of the Forgotten

The Powder of the Forgotten requires two essential items: the Necrofluid Gauntlet (wonder weapon), and the Wisp Tea perk. To start, you can get Wisp Tea from the Zarya Cosmodrome, or you can get it for free by completing the twins easter egg at Vandorn Farm (click here). With Wisp Tea, you will want to hang around the Tailor Shop in the eastern area of Ashwood, to the right of Vulture Aid. Inside is a mirror that Wisp Tea can destroy, so activate Wisp Tea by damaging zombies and let it interact with the mirror simply by being close to it.

Now, it’s time to get the Necrofluid Gauntlet. This is an extensive quest, but we’ve simplified it with a step-by-step guide on how to get the Necrofluid Gauntlet here for you to follow. With the Necrofluid Gauntlet acquired, head back to the mirror in Ashwood and shoot it, which will see the Powder of the Forgotten drop to the floor.

Serum Part #2 – Widow’s Lantern

To get the Widow’s Lantern serum part, you must first head to Blackwater Lake. Inside Blackwater Lake, you must enter the Cabin and head to the kitchen, which is in a downstairs room. Once you’re in the kitchen, look at the south wall, where, to the left, you will find a sink with a cabinet beneath it that contains the Jar of Spores that you can collect by interacting with it.

With the Jar of Spores acquired, take a trip to Vandorn Farm, where, just outside the main gate of Vandorn Farm, you’ll find a dead horse covered in mushrooms. Interact with the dead horse, and a red bulb will appear. Now, wait 3 entire rounds, and the spores will grow larger until you can eventually pick up the Widow’s Lantern.

Serum Part #3 – Mysterious Limb

The Mysterious Limb is a time-gated item, and you can only get one once Zursa the zombie bear spawns. Zursa is an Elite Enemy who spawns from Round 16 onwards, and once Zursa spawns, you will need to kill the bear with the Abomination Heads’ Beam Attack from Ol’ Tessie. This upgrade is acquired from Reba’s Diner at Exit 115 by killing the Cook zombie and taking the Freezer Key to open the southwest freezer, then by upgrading Ol’ Tessie at the garage in Ashwood. Feel free to weaken Zursa with your guns and then, when she’s almost dead, use the Beam Attack to finish her off, which will see her explode and drop the Mysterious Limb item to collect.

Serum Part #4 – Ravager Eyes

The Ravager Eyes can be acquired once a Ravager has spawned into the map. These enemies appear at random, or during Max Ammo rounds, and are noted for their fast movement on all fours. When you have a Ravager, lead it to any of the Saw Blade traps around the map. There’s one outside the Barn in Vandorn Farm. Activate the Saw Blade trap for 2,000 Essence and let it kill the Ravager, and it will drop the Ravager Eyes for you to pick up.

Serum Part #5 – Hoard Husk Chunks

To get the Hoard Husk Chunks, you must first get the Abomination Carcass upgrade for Ol’ Tessie. To do so, head into Reba’s Diner at Exit 115 and wait for a zombie to spawn called the Cook. This zombie will drop a Freezer Key. Then, head into the kitchen area and look at the southwest freezer, where you can interact with it to get the Abomination Carcass. With this item, head to Ol’ Tessie’s garage in Ashwood and upgrade it with the Abominations Head Beam Attack.

With the Abomination Heads on Ol’ Tessie, venture to the roads between locations with the infinite spawning zombies and look for a plant that glows purple. These can be found at random, so just drive around until you locate one, then use R1’s Beam Attack to shoot the plant, which will see the Hoard Husk Chunks drop as an item to collect. Just be careful getting out of Ol’ Tessie, as the zombies are extremely aggressive.

Serum Part #6 – Human Bones

The Human Bones is a serum part that can be acquired within Vandorn Farm, specifically in the Barn area. You will need both a Combat Axe and a Molotov for this quest, but they can be obtained for free. To get a Combat Axe, you can find one in the kitchen at Reba’s Dinner at Exit 115. Alternatively, you can get one for doing the Mr. Peeks axe-throwing easter egg found here. With the Combat Axe, head to the Barn and throw it at the hanging corpse’s right foot in the middle of the Barn. It’s the corpse hanging by its wrists. Doing so will see its foot fall off.

With the foot now on the ground below the corpse, throw a Molotov at the freshly cut foot. You can craft a Molotov at the Crafting Table in the Barn, or you can get one for free outside the Ol’ Tessie garage in Ashwood. Once the fire disperses, the foot will become the Human Bones that you can pick up.

How to Solve the Serum Puzzle in Ashes of the Damned

With all 6 Serum parts acquired, you will need to head to the Zarya Cosmodrome. Venture southwest of this location and enter Yuri’s Lab, where you will find the Serum parts you collected within separate bowls, and some chemistry equipment. To begin, interact with the Powder of the Forgotten found in the 5th bowl, and the vials will begin to puff in smoke. After the smoke has cleared, three distinct words will appear on the chalkboard, but they’re unique symbols using the Pigpen cipher. However, you won’t need to use that, as we’ll translate what each of the words means and which bowl you will want to interact with. The goal is to interact with the correct bowl in the correct sequence, which will be the top symbols, then the middle symbols, then the bottom symbols. The codzombiessolver.com site can help if you’re struggling, but we’ll translate them in the image above and in text below:

> – Human Bones (1st bowl)
L – Hoard Husk Chunks (2nd bowl)
C – Widow’s Lantern (3rd bowl)
C. – Ravager Eyes (4th bowl)
L. – Mysterious Limb (6th bowl)

After you have interacted with the correct 3 bowls in the right order, the vials will begin to ooze a red smoke, and you will then need to interact with the central vial to trade some of your blood. Doing so will start a lockdown sequence where you have to kill zombies, but be warned, as your health will not regenerate during this lockdown. To heal, you need to use the Necrofluid Gauntlet’s primary fire button, then reload, as it will siphon health from defeated enemies. After the lockdown sequence, the puzzle will be completed!