Finishing the Serum sequence in Ashes of the Damned is widely considered one of the most demanding stages of the Call of Duty:Black Ops 7 Zombies main Easter egg. The challenge comes from a mix of delayed enemy spawns, specific kill conditions, environmental interactions, and a final alchemy-style puzzle that punishes mistakes. For solo players or first-time runners, it can easily feel like a brick wall – until you understand how each step fits together.

Below is a fully reworked, step-by-step breakdown that simplifies the process from start to finish.

All Serum Part Locations in Ashes of the Damned

Serum Part 1 – Powder of the Forgotten

To obtain this component, you'll need Wisp Tea and the Necrofluid Gauntlet.

Start by acquiring Wisp Tea. You can either purchase it at Zarya Cosmodrome or earn it for free by completing the Twins Easter egg at Vandorn Farm. Once the tea is active, travel to the Tailor Shop in eastern Ashwood, near Vulture Aid. Inside the building is a mirror that reacts only while Wisp Tea is active. Stand close to it to cause the mirror to shatter.Take full control of your grind with MMOexp Black Ops 7 Bot Lobbies. From testing Lethal Equipment to perfecting high-round routes, our bot lobbies help you optimize every aspect of your gameplay—without wasted time or frustration.

Next, secure the Necrofluid Gauntlet. Return to the broken mirror and shoot it with the gauntlet equipped. This will cause the Powder of the Forgotten to drop on the floor.

Serum Part 2 – Widow Lantern

Make your way to Blackwater Lake and enter the cabin. Head downstairs into the kitchen and open the cabinet beneath the sink on the southern wall to collect a Jar of Spores.

Bring the spores to Vandorn Farm, just outside the front gate, where a deceased horse covered in fungus can be found. Interact with the body to plant the spores. After waiting three full rounds, the growth will mature, allowing you to collect the Widow Lantern.

Serum Part 3 – Mysterious Limb

This item is tied to Zursa, the elite zombie bear that begins spawning from Round 16 onward.

To secure the drop, Zursa must be killed using Ol' Tessie's Abomination Head Beam Attack. First, unlock the Abomination Head upgrade by defeating the Cook zombie at Reba Diner (Exit 115), obtaining the Freezer Key, and completing the Ol' Tessie upgrade path in Ashwood.

Once Zursa spawns, weaken her with standard weapons. When her health is low, finish her with the Beam Attack. If done correctly, she will explode and drop the Mysterious Limb.

Serum Part 4 – Ravager Eyes

Ravagers are fast, quadrupedal enemies that can appear randomly or during Max Ammo rounds.

When one spawns, lure it toward a Saw Blade trap, such as the one located outside the Barn at Vandorn Farm. Activate the trap for 2,000 Essence and allow it to kill the Ravager. The enemy will automatically drop the Ravager Eyes upon death.

Serum Part 5 – Hoard Husk Chunks

This step also requires the Abomination Head upgrade for Ol' Tessie.

Drive Ol' Tessie along the connected roadways and watch for purple-glowing plants, which spawn at random locations. When you spot one, use the Beam Attack to destroy it. The Hoard Husk Chunks will drop immediately.

Be careful when exiting Ol' Tessie—zombies in these areas are extremely aggressive and can overwhelm you quickly.

Serum Part 6 – Human Bones

Head to the Barn at Vandorn Farm. You'll need a Combat Axe and a Molotov, both of which can be obtained without cost. The Combat Axe is found in the Reba Diner kitchen, while Molotovs can be crafted inside the Barn or collected near Ol' Tessie's garage.

Inside the Barn, locate the hanging corpse in the center. Throw the Combat Axe at the right foot of the body to knock it down. Once it falls, throw a Molotov onto the foot. After the flames burn out, the Human Bones will be available to pick up.

Once all six Serum components are collected, travel to Yuri's Lab, located southwest of Zarya Cosmodrome. Inside, you'll see six bowls containing your items, along with a chemistry station in the center of the room.

Begin by interacting with the Powder of the Forgotten, which sits in the fifth bowl. This triggers a smoke effect that fills the room. When the smoke clears, three Pigpen cipher symbols will appear on the chalkboard. These symbols indicate the exact order in which three bowls must be activated—top symbol first, then middle, then bottom.

To save time, here is the correct translation:

> = 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)

Activate the three correct bowls in the displayed order. If done successfully, the vials will emit red smoke. Interact with the central vial to exchange blood and initiate the lockdown phase.

During the lockdown, health regeneration is disabled. The only way to heal is by using the Necrofluid Gauntlet's siphon mechanic—fire the weapon and reload to drain health from nearby zombies.

Survive the lockdown sequence, and the Serum puzzle will be officially complete.

Because of the strict requirements and failure penalties, many players practice this entire chain in CoD Black Ops 7 Bot Lobbies for sale before attempting it in a real match. Rehearsing complex Easter egg steps without external pressure can dramatically improve consistency, especially for solo runs.