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Destiny 2 Duality Dungeon Guide – How to Complete Every Encounter

The Upside Down

Destiny 2 Season of the Haunted is here, and it’s the spookiest addition yet. With the return of Emperor Calus’ mighty Leviathan, players are tasked with venturing into this massive ship to deduce what has happened to this corrupted vessel. Along with the new Nightmare Containment activity, players can earn new weapons, armor, and cosmetics for your Guardian.

One of the coolest additions is the new Duality dungeon, which has players entering Calus’ mind to try and uncover his secrets. Broken up across three major encounters and one small puzzle, this dungeon can be pretty tricky to figure out. With quite a few different mechanics, below is a detailed breakdown of how to complete every major encounter in the dungeon. I won’t be going over the jumping puzzles here, simply because they are extremely straightforward and it’s difficult to get lost. Additionally, this will not be going over the collectibles hidden within, simply the encounters themselves.

For those looking for all the Repressed Memory collectibles, here’s our guide on their locations.


Bell of Conquest Mechanic

The big gimmick of this dungeon is the Bells of Conquest. When shot, these bells will transport everyone in the fireteam to the nightmare realm regardless of where they are. You can also shoot the bell to return to reality; however, you need to be in a safety circle around the bell to not die when going from the nightmare to the normal world. These will be in both the jumping puzzles and encounters so get used to shifting between realms.

Nightmare of Gahlran

The Nightmare of Gahlran is your first encounter and boss in Duality. This fearsome foe might seem intimidating, but this is a pretty simple fight. When the encounter begins, shoot the bell and warp to the nightmare world where Gahlran is running around. On either end of the arena are two bells which have rooms on either side of the bells. When you arrive in the nightmare, have one person kill all the Bellkeepers that spawn while the other two players check the side rooms on either side of the bells. The Bellkeepers will always spawn across from the bell you rang, so if you rang the top bell, they will be on the lower section or vice versa.

Two of the four rooms will have War Beasts and a Standard Bearer Psion. Killing the Psion will cause a Standard (it looks like a giant key) spawn, which will be designated as Chalice, Sun, Dog, or Axes. You can tell which one you get because you’ll have a buff on the left side of your screen that reads Standard Essence (Chalice).

Once both people acquire their Standard Essence, make your way back to the bell and return to the normal world. More enemies will spawn here and two rooms will have white glowing symbols on the floor that correspond to which Standard Essence you have (shown above). So if you found Axes and Sun, you need to deposit the Standard Essence onto the correct symbol. This will open up a door right by the symbol where some War Beasts and a Colossus spawn.

Kill the enemies and then have each player who deposited a Standard Essence go into the room where the Colossus enemies spawned. The third should stay in the middle of the room. Shoot the lantern to warp back into the nightmare world and kill the Visions of Gahlran that appear. Both sides will need to kill all of their visions to trigger a damage phase. Simply follow the path and kill any Visions of Gahlran that spawn until you reach the end, causing the door to open to the main room.

The person in the middle will need to kill the Bellkeepers so you can leave before the nightmare collapses and wipes your team. Once both sides are clear, meet up in the middle and damage the boss. My team found that swords were especially effective since this boss likes to get in close, which makes using rocket launchers and snipers a bit awkward. Also, keep an eye on the Nightmare Collapsing timer on the left side of your screen. When it hits around 12 seconds, make your way to a bell and warp back to reality.

This will conclude the damage phase. Now simply repeat the steps above until you kill the Nightmare of Gahlran. There’s no time limit on the encounter itself, so if you need to go extra damage phases, that’s totally fine! There are also no resurrection tokens, so you can theoretically die as many times as you want.

Statue Puzzle Room

After you complete the jumping puzzle, you will arrive in a large room with a bell in the center and four statues of Cabal Bathers pointing in different directions. Go into the nightmare realm by shooting the bell and approach the statue’s base to find a dial shaped like Calus’ head (shown above). Interacting with this causes the statues in reality to rotate. Make all of the statues in reality point their swords toward the middle to open up the door under the bell.

Unlock the Vault

Before you begin this encounter, I recommend throwing on any roaming Supers and mob-clearing weapons like machine guns or grenade launchers. Once you start the encounter, a bunch of enemies will flood the room from all sides, including a mini-boss you cannot kill. Additionally, two symbols (Chalice, Sun, Dog, or Axes) on the floor will appear.  Clear the room of enemies and kill the Bellkeepers that spawn underneath the staircase on the lower level of the arena — there will be four in total. After the Bellkeepers are dead, locate the wall that has the same matching symbol as one on the floor (shown above). Have one teammate stand by each of the corresponding walls before the third shoots the bell to send everyone to the nightmare realm.

When you arrive, the middle person just needs to clear enemies and kill the Bellkeepers on the lower floor so you can exit. As for the other two, head up the stairs and kill every enemy on this level including the Colossus — this will cause a Standard Bearer to spawn along with some War Beasts. Slay the Standard Bearer and collect the Standard Essence that spawns. Killing a Standard Bearer will also increase your Nightmare Collapsing timer by 10 seconds!

Head back to the middle where your third teammate is and go to the normal reality via the bell. Deposit the Standard Essence into the correct symbol to make the mini-boss vulnerable. Kill all of the enemies and the mini-boss to make another collection of symbols appear on the floor. Another mini-boss will then spawn.

Repeat the process of going into the nightmare realm, collecting the Standard Essence, returning to reality, depositing the Standard Essence, and killing the mini-boss two more times. After the third one is killed, the encounter will end and you can grab the chest when the floor opens up.

Nightmare of Caiatl

Welcome to the final boss. For this encounter, you will be doing what you have been doing in the entire dungeon thus far, just on a bigger scale. When the battle starts, a ton of enemies will spawn, so focus on killing them quickly. Specifically, the sniper Psions in the back can be a real nuisance if left unchecked, so make sure to prioritize them. Just like in the other encounters, two symbols will appear on either side of the room near the large chains. You will also have six Bellkeepers spawn — two in the middle, two on the right, and two on the left.

After the Bellkeepers are killed, locate the balcony with the same symbol as one of the symbols on the floor. Have one person stand on each balcony while the third hangs out in the middle. Shoot the Bell of Conquest to transport yourself to the nightmare realm. The people on the balconies will have a Psion Standard Bearer spawn right next to them — kill the Psion and collect the Standard Essence that spawns on this platform. You will also want to kill the Colossus enemies on the far side of the arena because they can blast you off the balcony.

Unsurprisingly, the person in the middle will need to kill all the Bellkeepers that spawn. The Standard Essence collectors can also help with this since they will most likely finish their task in a couple of seconds. There are a lot of enemies in the middle, so you’ll want to be careful — if you die with a Standard Essence, it won’t respawn until you re-enter the nightmare realm again. After the Bellkeepers are dead and the Standard Essence is collected, go back to the real world and deposit the essence into the correct symbol. The bell you can exit from will always be the one you enter the nightmare realm with.

You will need to repeat this entire process once more so a total of four Standard Essence have been used.

After all four are placed, the chains will have an odd red glow to them. Clear out some of the enemies, collect ammo, and then shoot the side of one of the chains. This will cause them to rise, ringing the massive bell in the back of the room. All three of you will now warp back into the nightmare realm where the damage phase begins.

Now you and your team will need to kill all of the Bellkeepers in the room — specifically the ones at whichever bell Caiatl runs towards. These bells are middle, left, and right, so if she runs to the right, you need to very quickly kill every Bellkeeper on the right and then go stand next to the bell. Once your team is next to the bell, shoot it to make it ring out and stun Caiatl. This will buff you, allowing you to do a lot of damage to her before she moves on to the next bell in the room.

Remember, if you aren’t next to the bell when it goes off, you will only do 10% damage to Caiatl. Repeat this process of killing the Bellkeepers, ringing the bell to stun her, and damage until all three bells have been used. You will then return to reality, where the entire cycle starts over again until she is defeated.

If you’re looking for more help, we have guides covering how to unlock the Solar 3.0 fragments and grenades, how to get the new Jotunn catalyst, how to farm Vestiges of Dread and Opulent Umbral Energy, all Exotics, new weapon Patterns, seasonal mods, and Season of the Haunted triumphs. In addition, we’re covering all patch notes, bugs and top issues, Bound in Sorrow quest steps, and Calus Bobbleheads. We’ve covered how to get Opulent Keys, Bound Presence in Containment, Crown of Sorrow H.E.L.M. upgrades, Iron Banner Seal Triumphs, and the Trespasser Catalyst. And lastly, we’ve written on how to find a Loyalist Commander for Battles Lines Triumph and the Cek’ik Boss.

About the Authors

Collin MacGregor

Collin MacGregor is the Guide Staff Writer at Fanbyte. He's also the person who willingly plays the support class (you're welcome) and continues to hold out for an Ape Escape remake.

Dillon Skiffington

Dillon is the Senior Game Guides Editor at Fanbyte. He's been writing about video games for 15 years and has thousands of hours logged in FFXIV and hundreds of hours in Destiny 2.