You're standing in the middle of a medieval fortress, surrounded by the undead, and honestly, the game doesn't give you much to go on. Citadelle des Morts, the latest round-based map in Call of Duty: Black Ops 6, is a labyrinth. If you’ve played Zombies since the World at War days, you know the drill: find the power, build the Pack-a-Punch, and then descend into the absolute madness of the main quest. This isn't just about shooting heads. It's about a complex, multi-stage ritual that ties back into the Dark Aether lore in ways that actually make sense for once.
The easter egg citadelle des morts isn't just a trophy hunt. It’s the way you unlock the true ending of the map, and frankly, if you aren't doing it, you're missing out on the best weapon upgrades and the most satisfying boss fight we've seen in a while.
Getting Started Before Everything Goes to Hell
First things first. Stop trying to do the main quest on round 5. You’ll die. You need to get the power on—that’s basic—but you also need to focus on the Hydro-Electric Power and the Subterranean areas early. The map is vertical. Use that. Once you have the power humming, your first real goal for the easter egg citadelle des morts is the Gargoyle Statues.
People always mess this up because they think they can just interact with them. You can't. You need the Essence Trap or the specific Wonder Weapon for this map, the Scourge of the Citadel. If you haven't pulled it from the Box, you'll have to build it. Building it involves finding the three distinct pieces: the hilt, the crystal, and the scorched blade. These are scattered around the Ramparts and the Alchemist's Lab. Don't rush. The zombies get faster, and the Tight Corners in the Citadelle are death traps.
The Ritual of the Three Bells
Once you've got your gear, you need to find the bells. There are three of them. They aren't just for decoration. They correspond to specific frequencies that resonate with the Dark Aether. You have to hit them in a specific order that changes every single match based on the symbols found in the Library. Check the walls. Look for the glowing blue chalk. If you see a symbol that looks like a crescent moon, that’s your starting point.
Hit the first bell. You’ll hear a low hum. If it sounds like a screech, you messed up the order. Reset.
🔗 Read more: Lust Academy Season 1: Why This Visual Novel Actually Works
The second bell is usually located near the Executioner’s Block. It’s a grim spot, but necessary. After the third bell is rung correctly, the ground will literally shake. This triggers the mid-round "mini-boss" spawn. It’s usually a corrupted knight or a heavy armored variant. Kill it immediately. It drops the Resonance Key, which is vital for the next step of the easter egg citadelle des morts.
The Alchemist’s Puzzle and the Potion Trap
This is where most players quit. The Alchemist's Lab is a nightmare of colored liquids and pressure plates. You have to mix a specific concoction to "cleanse" the Resonance Key. Look at the jars on the shelf. You need the Sulfur, the Mercury, and the Salt.
Wait.
Did you check the blackboard? There’s a formula written there. It’s not just flavor text. The formula tells you the ratio. Usually, it's 2 parts Sulfur to 1 part Mercury, but keep an eye out for variations. If you mess up the mix, the lab fills with toxic gas. You’ll lose your armor in seconds. It's brutal. Once the key is cleansed, take it to the Iron Maiden in the basement.
Inside the Iron Maiden, you’ll find the remains of a former researcher. Place the key in the slot. A cinematic will trigger—don't worry, zombies won't kill you during this specific 5-second window—and the door to the Inner Sanctum will finally unlock.
💡 You might also like: OG John Wick Skin: Why Everyone Still Calls The Reaper by the Wrong Name
Defending the Soul Canisters
Now, things get loud. You’re in the Sanctum. There are four canisters in the corners of the room. You have to fill them with souls. This is classic Zombies gameplay, but with a twist: the canisters emit a pulse that drains your health if you stay too close for too long. You have to dance in and out of the radius.
Use your Wonder Weapon here. The Scourge of the Citadel's secondary fire creates a vortex that pulls zombies toward the canisters. It makes this step ten times easier. If you're playing solo, use Decoys. Monkeys work too, but Decoys give you more breathing room to focus on the heavy hitters that spawn in.
The Boss Fight: The Corrupted Sentinel
You’ve done the bells. You’ve mixed the potions. You’ve filled the souls. Now, the easter egg citadelle des morts culminates in a fight against the Corrupted Sentinel. This thing is huge. It’s a fusion of medieval armor and Aetherial energy.
The fight has three distinct phases:
- The Shield Phase: The Sentinel is invincible behind a wall of floating debris. You have to shoot the glowing blue orbs orbiting its head. Don't aim for the body yet. It’s a waste of ammo.
- The Fire Phase: The floor becomes lava. Literally. Stay on the raised platforms. The Sentinel will swing a massive flail that can one-shot you if your armor is down. Jump or slide to avoid the shockwaves.
- The Final Stand: The Sentinel loses its armor. It becomes faster. It teleports. This is when you dump every bit of ammo, every grenade, and every killstreak you have.
When it drops, don't just stand there celebrating. You have to interact with the Core in the center of the arena to trigger the final cutscene and the exfil sequence.
📖 Related: Finding Every Bubbul Gem: Why the Map of Caves TOTK Actually Matters
What Most People Get Wrong
I see a lot of talk online about the "hidden" fourth bell. It doesn't exist. People get confused because of the ambient noise in the Courtyard. Don't waste your time looking for it. Also, the Magnifying Glass item? That's for a side easter egg, not the main quest. If you're trying to speedrun the easter egg citadelle des morts, ignore the side quests until the Sentinel is dead.
Another big mistake is the Perk selection. You need Stamin-Up. The Citadelle is too big and the boss moves too fast to be sluggish. Jugger-Nog is a given, but Quick Revive is actually more important in the final phase because of the health regeneration boost.
Actionable Steps for Your Next Run
If you want to actually beat this thing tonight, follow this exact sequence.
- Round 1-5: Farm points. Don't buy any doors until you have enough to reach the Power Room in one go.
- Round 6-10: Build the Wonder Weapon. Don't rely on the Box; the RNG will ruin your run.
- Round 11-15: Complete the Bell and Alchemist steps. The zombies are still slow enough that you won't get trapped in the Lab.
- Round 16+: Fill the canisters and enter the boss fight. Any later than Round 20 and the Sentinel’s health scaling makes the fight an absolute slog.
Pack-a-Punch your primary weapon to at least Level 2 before entering the Sanctum. If you have a Legendary Tool, use it on the Scourge. The damage tick on the vortex is what wins the soul-filling stage.
Once the Sentinel is down, grab the Aether Tool reward immediately. It drops right at his feet. Use it on your secondary weapon before the exfil chopper arrives. You’ll get a massive XP boost for "Perfect Exfil" if all players are on the bird when it lifts off.
Get back in there. The lore bits you find in the final room after the boss dies hint at the next map, and you'll want to see those coordinates for yourself. Check the desk behind the primary console; there’s a small radio that plays a message from Dr. Peck. It changes the whole context of why we're even in the Citadelle.
Stop overthinking the symbols. Draw them on a piece of paper if you have to. It's better than forgetting them mid-round and having to run back across the map while three Manglers are chasing you. Good luck. You're going to need it for that final phase.