How to beat the Destiny 2 Duality Dungeon

In the Destiny 2 Duality Dungeon, you’ll enter the Mindscape of Emperor Calus to confront Nightmares from his past. Start by picking up the ‘A Single Thread’ quest from Suraya Hawthorne, then you can pay a visit to the Derelict Leviathan on the Moon and delve into Calus’ broken mind. You’ll be using bells to transport you and your fireteam between the Mindscape and Nightmare realms, fighting legions of Cabal Loyalists and figures from Calus’ past if you are to emerge victorious and get some lavish loot. Here’s how to complete the Destiny 2 Duality Dungeon.

Destiny 2 Duality Dungeon encounters

• Duality intro and bell mechanic
• Nightmare of Gahlran boss
• Secret loot chest 1
• Unlock the vault
• Secret loot chest 2
• Nightmare of Caiatl final boss
• Duality rewards and loot

Destiny 2 Duality Dungeon intro and bells explained

As you land in the Duality Dungeon, you’ll appear in the old Tribute Hall aboard the Leviathan where Eris will explain what your mission is. Hop into the hole in the floor that opens where the statue of Calus is be transported to the Mindscape. You’ll emerge into a small room with a window grate that looks a lot like the interior of the Leviathan.

Through the window grate, you’ll notice a large, glowing bell at the other end of an open area. If you damage it enough, it’ll close and transport you and your fireteam to a red Nightmare realm. For the purposes of this guide, we’ll refer to the normal Mindscape realm that usually has a soft, blue light as “Blue”, and the red Nightmare realm as “Red”.

Now that you’re in Red, run to the bell you just shot, stand next to it, and shoot it again. This’ll transport you and any fireteam members near the bell back to Blue. If you are not next to a bell when it is activated in Red, you will die, but it is safe to shoot a bell from anywhere while in Blue. Good communication with your fellow Guardians is key to ensuring you don’t accidentally kill each other and get separated when going between Blue and Red.

These mechanics persist throughout the entire dungeon and are especially integral to all three of its encounters. Make sure you’re also looking out for bells that you can use to reach new places when navigating between encounters. With that, progress up and through the Dungeon using the bells until you reach a large chamber with a shallow pool and lots of Cabal Loyalists inside. Defeat them all and jump through the door that opens in the floor to reach the first encounter.

Destiny 2 Duality Nightmare of Gahlran boss fight

The first encounter of the Duality Dungeon sees you facing off against the Nightmare of Gahlran, Sorrow Bearer. Gahlran lives in Red but is immune to all damage, so the objective is to make him vulnerable by using the essences of Cabal Standards to unlock doors in Blue and then using the bells to reach areas in Red that are usually sealed off.

The Blue area in this encounter features two bells: one that’s at the top of some steps – the top bell – and one on the opposite end of the room – the bottom bell. There are also four slots for Cabal Standards clearly marked with symbols, which you’ll need to activate to open the doors leading to side rooms behind each slot. The Sun and Chalice Standard slots and side rooms are on either side of the upper bell, and the War Beast and Axe slots and side rooms are on either side of the lower bell.

The Red area has pretty much the same layout, but you’ll notice that some of the doors by the Standard slots that are closed in Blue are open here. The major difference in Red is that you have one minute before the Nightmare collapses, meaning you will die if you’re still there when the timer ends. Make sure you leave yourself plenty of time to get to and activate a bell to safely return to Blue. Both areas also feature Elite Cabal Incendiors called ‘Bellkeepers’ who arrive in pairs to block each bell. They must be defeated to make a bell usable again.

For this encounter, we recommend that you use any high burst damage weapons and Supers – check out our Destiny 2 Class guide for more information, but things like Thundercrash, Nova Bomb, and Blade Barrage will be great choices – as your damage windows against Gahlran can be quite short. A weapon with decent range is also useful for dealing with Psion snipers in Red.

Here’s a rundown of what you need to do to beat the Nightmare of Gahlran:

1. Shoot one of the bells to get all three players to Red.
2. Players 1 and 2 find and kill the two Psion Standard Bearer enemies that are in two of the four side rooms and retrieve their Standards, paying attention to the Standard’s symbol – killing a Standard Bearer grants a 15-second time extension too.
3. At the same time, Player 3 destroys the pair of Bellkeepers near the top bell and clears other enemies to help Players 1 and 2 safely return to the bell. Aside from the Psion snipers, the top bell is the safest of the two as Gahlran and most of the other Cabal enemies can’t reach it.
4. Shoot the top bell to go back to Blue.
5. Players 1 and 2 deposit their Standards at the correct Standard slots. This will open the door to the nearby side room at each Standard slot.
6. All players should focus on clearing the area of the Bellkeepers and Elite Colossuses that walk out the side rooms.
7. Once most of the enemies are dead, Players 1 and 2 must head into their respective side rooms and then Player 3 will shoot the top bell to take everyone back to Red.
8. Players 1 and 2 will be trapped in the Red versions of their side rooms with six Visions of Gahlran each. They must find and kill them all as quickly as possible and then escape through the exit door into the main area of Red – each Vision killed adds a few extra seconds to the Nightmare Collapsing timer.
9. Meanwhile, Player 3 destroys the pair of Bellkeepers near the top bell and then clears other enemies.
10. Once all the Visions of Gahlran are dead, the Nightmare of Gahlran will be vulnerable, so go wild with Supers and heavy weapons to deal as much damage as possible to the boss.
11. Keep an eye on the timer. Once it reaches 8-10 seconds, go back to the top bell and shoot it to return to Blue.
12. Defeat the Bellkeepers, then repeat these steps until the Nightmare of Gahlran is dead.

With the Nightmare dead, your loot chest will be waiting for you in Blue and a hatch in the floor will open, allowing you to go deeper and find the next encounter. You’ll be faced with more platforming and then a puzzle room involving a bell and some Cabal statues.

To solve this puzzle and open the vault door under the bell, you need to get all the statues in Blue pointing their axes towards the bell. You can rotate the statues in Blue 90-degrees anti-clockwise by activating the button on the base of the same statue in Red.

Destiny 2 Duality secret chest 1

Before you jump down the vault door in the statue puzzle room, there’s a secret chest for you to find. This room has a few elevated platforms with doors on them, much like the one you used to get inside this room. The doors on one of these platforms are slightly ajar and you can go into a small room to loot a secret chest. You can use Destiny 2 Opulent Keys to open similar looking chests while patrolling the Derelict Leviathan too.

Destiny 2 Duality unlock the vault encounter

For the second major encounter of the Duality Dungeon, you’ll need to go through a similar set of steps to the Nightmare of Gahlran encounter, except opening the vault requires you to defeat three smaller Cabal bosses one after the other:

• Nightmare of Ka’hok, Sworn of Umun’arath
• Nightmare of Emonut, Sworn of Moli Imoli
• Nightmare of Uroa, Sworn of Shayotet

These bosses are found in Blue, but, like before, you’ll need to go to Red to defeat Standard Bearers, get Standards, and deposit them back in Blue to make them vulnerable to damage.

The Blue vault area centers around the circular vault door on the floor, which is surrounded by six Standard slots. Two of these slots will present a random symbol. There is also a bell at the top of some steps – top bell – and one on the opposite end of the room – you guessed it, bottom bell.

The Red version of this area is much bigger and features four extra areas that link to a particular symbol. The left of top bell is War Beast and the right is Axe, while the left of bottom bell is Chalice and the right is Sun. As before, the one-minute Nightmare Collapsing timer is also there to kill you if you spend too long in Red, so ensure you’ve got time to get back to a bell. The vault door in the middle is also replaced by a giant pit so don’t stand in the middle area in Blue when you are heading to Red.

Bellkeepers will be in both Blue and Red to protect the bells and they appear in a lower section under each bell. Do note that only one pair spawns in Red, which means you won’t have a choice in which bell you can use.

The bosses in this encounter aren’t particularly strong, but they’re reinforced by the endless Cabal foes that flood almost every area, so any protective abilities, such as Ward of Dawn and Well of Radiance will be useful. Roaming Supers that can clear a lot of enemies quickly, like Stormtrance or Fists of Havoc will be good to have too.

Here’s what you need to do to unlock the vault in the Destiny 2 Duality Dungeon:

1. Check the two symbols that appear on the Standard slots and remember what they are.
2. Defeat both pairs of Bellkeepers, then shoot either of the bells to get all three players to Red.
3. Players 1 and 2 each take one of the areas that corresponds to the Standard symbols and kills every enemy there. Watch out for the Colossuses that stand at the far end of each area.
4. Once everything in an area is dead, a Standard Bearer Centurion will spawn along with lots of War Beasts. Both players need to kill their Standard Bearers, collect the Standard, and then head back to the bell.
5. While this is happening, Player 3 needs to find and kill the pair of Bellkeepers and then keep the active bell clear of enemies.
6. All players must gather around the bell and shoot it to go back to Blue.
7. The players with the Standards needs to deposit them at the correct slots.
8. This will start the damage phase for the first boss, so throw everything you’ve got at them.
9. After they’ve been defeated, two more symbols will appear in the next two Standard slots, so you’ll need to repeat everything twice more to get the next two bosses and complete the encounter.

If your team is struggling to defeat the enemies and collect the Standards in Red before time runs out, you can send both players to get one standard, go back to Blue, deposit the Standard, and then go back to Red to get the second Standard.

After all three Nightmares have been defeated, the vault door in the center will open and you can jump down to collect your loot. Continue running through the Mindscape to progress and reach the second secret chest, then onward to the final boss.

Destiny 2 Duality secret chest 2

After opening the vault and running through the Mindscape a bit more, you’ll reach an area called ‘The Depths’ and a large room with a black object covered in a white cloth in the middle. Go under the object and look for the crawlspace that you can crouch into that’s in the walkway closest to the entrance of this room. There is another secret chest in the crawlspace.

Destiny 2 Duality Nightmare of Caiatl boss fight

You’ve made it to the third and final encounter of the Duality Dungeon: a boss fight against the Nightmare of Caiatl, Princess-Imperial. This is going to combine everything you’ve learned from the previous two encounters as well as a new and slightly complicated damage mechanic for bringing the Nightmare of Caiatl down.

The Blue arena for this boss fight features three bells – left, middle, and right – and one massive bell at the far end of the arena, the Bell of Conquest. This bell is very important later, and you’ll easily spot that there are four Standard slots in front of the four chains that hold up the bellringer. You’ll also notice the four small platforms in the arena that link to the Standard symbols – War Beast and Sun are on the left wall and Chalice and Axe are on the right.

The Red version of this arena is largely the same except for the fact that every bit of floor in Blue that is made of a purple crystal-like material does not exist in Red, so you can very easily fall to your death in the Red arena. The symbol layout across Both Red and Blue is the same though, and you’ll be used to the Nightmare Collapsing timer by now. Pairs of Bellkeepers will be in both Blue and Red to protect the three bells, although Red will only have one usable bell, but all six Bellkeepers must be killed to use it.

While Caiatl isn’t too tough of a boss, this encounter can be tricky because of the ridiculous number of enemies that spawn. Psions, Centurions, War Beasts, Bellkeepers, and Colossuses are everywhere, so you’ll need a weapon loadout that suits clearing lots of enemies of varying levels of toughness. As for defeating Caiatl, she has a several very short damage windows, so we recommend quick, high-damage Supers as with Gahlran to wear down her health bar quickly.

This is what you need to do to defeat the Nightmare of Caiatl and beat the Destiny 2 Duality Dungeon:

1. Check for the two symbols that appear on two of the four Standard slots and remember what they are.
2. Defeat any pair of Bellkeepers to reactivate a bell and allow Players 1 and 2 to get on top of the platforms that correspond with the two symbols
3. Shoot the bell to get all three players to Red.
4. Players 1 and 2 must quickly kill the Psion Standard Bearer on their platform and then grab the Standard.
5. At the same time, Player 3 should start killing all six Bellkeepers in the area. Once Players 1 and 2 have their Standards, they can help with this.
6. With all the Bellkeepers gone, all players need to head to the active bell and shoot it to go back to Blue.
7. The players with the Standards must deposit them in the correct slots. Be aware that lots of enemies will start spawning now.
8. A new pair of symbols will appear, so repeat steps 2 through 7 for this new pair.
9. Once four Standards have been deposited, the Bell of Conquest is primed to ring. Shoot any of the glowing red gemstones on the golden chains in the middle area to ring the Bell of Conquest. This will teleport all players to Red and begin the damage phase against the Nightmare of Caiatl.
10. As you all arrive in Red, spread out and start trying to kill the pairs of Bellkeepers. Caiatl is has incredibly high damage resistance at this point so do not damage her now.
11. After a few seconds, Caiatl will start running towards one of the bells (left, middle, or right). All players must focus on killing the pair of Bellkeepers at this bell and then need to stand around the bell ready to shoot it before Caiatl reaches it.
12. Shoot the bell once Caiatl gets close to stun her and deal massively increased damage.
13. After she recovers, she’ll run to another bell. Kill the Bellkeepers, gather around the bell, and shoot it before she gets too close again for another damage window.
14. Kill the final pair of Bellkeepers, and stun Caiatl at the final bell for the last damage opportunity of this phase. Once Caiatl recovers, she’ll teleport herself and the whole team back to Blue.
15. Repeat all these steps until the Nightmare of Caiatl is dead.

The timing for the damage phase against Caiatl might take you a few tries to get down, but luckily there isn’t a Nightmare Collapsing timer, an encounter timer or Enrage mechanic that limits your damage opportunities as seen in Raids. Be aware that shooting the bell too early when she is too far away will cause her to just change course and head for another bell. Leaving it too late and letting her activate a bell will cause her to immediately teleport herself and the whole fireteam back to Blue, meaning you miss out on any damage.

With the Nightmare of Caiatl defeated, Eris will pull you back to the Tribute Hall where you started the Duality Dungeon and you can collect your final bits of loot.

Destiny 2 Duality rewards

The Duality Dungeon offers lots of unique rewards and even has uncapped loot, meaning you’ll get loot every time you complete an encounter, even if you’ve already completed it for the week - make sure you know when the Destiny 2 weekly reset is for other activities. The first two encounters drop one item each, and the final encounter drops two, so that’s four bits of loot, plus the two secret chests, although these chests only give you Duality loot that is already in your collections, so you won’t get anything new.

From the encounters, you can get the new Hakke armory-themed Deep Explorer armor sets for each Destiny 2 Class as well as new weapons, including a fancy Exotic Sword:

1. Heartshadow Exotic Sword: Charged heavy attacks turn you invisible and fire exploding Void projectiles. Remaining invisible with this weapon briefly increases its damage and Void projectiles weaken enemies if they hit while you are invisible.
2. Lingering Dread Special ammo Grenade Launcher
3. New Purpose Pulse Rifle
4. Stormchaser Linear Fusion Rifle
5. Unforgiven Submachine Gun
6. Fixed Odds Machine Gun (reprised Menagerie loot from Season of Opulence)
7. The Epicurean Fusion Rifle (reprised Menagerie loot from Season of Opulence)

Complete Duality on Master difficulty to get yourself Artifice Deep Explorer armor which comes with an extra mod slot to help your builds – perhaps you might need it for a hot Destiny 2 Solar 3.0 build. There are also plenty of Triumphs to get, secret Repressed Memories to find, an Exotic Ship to unlock, and a Seal and title to earn.

If you're looking for more high-difficulty PvE activities, why not get a few more players together and try the Vow of the Disciple Raid? There's a rotating challenge each week, ranging from the first encounter's Destiny 2 Swift Destruction challenge, to the Destiny 2 Looping Catalyst challenge against final boss, Rhulk.

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