GamesRadar+ is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Here’s why you can trust us

By Will Sawyer published 30 May 22

Enter Calus’ mind and beat the Destiny 2 Duality Dungeon

The Destiny 2 Duality Dungeon sees you entering the Mindscape of Emperor Calus to fight Nightmares from his past. You’ll need to first pick 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 the traumatized mind of the Calus. You’ll be using bells to transport you an your fireteam between the Mindscape and Nightmare realms and must face figures from Calus’ past if you are to emerge victorious and get some sweet new loot. Here’s how you can complete the Destiny 2 Duality Dungeon.

Duality is available to any player that owns either the Destiny 2 The Witch Queen digital deluxe edition or the Dungeon Pass – The Season of the Haunted Season Pass will not give you access to Duality, unfortunately. Even if you have either of those premium passes, you’ll be unable to begin the Duality Dungeon until you’ve picked up the ‘A Single Thread’ quest.

Head to Suraya Hawthorne in the Tower Bazaar and she’ll give you the quest, the first step of which is to simply complete the Dungeon. You’ll now have access to Duality and can launch it by opening the Destinations page, selecting the Moon, and then selecting the Duality Dungeon node below the Derelict Leviathan landing zone node.

Look out for Destiny 2 Calus Bobbleheads hidden across the Derelict Leviathan when patrolling

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 an area that looks a lot like the interior of the Leviathan.

Through the window grate, you’ll notice a large, glowing bell. If you shoot 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 – when in Red, you’ll notice a column of dark fog surrounding the bell which indicates the area you need to stand in. If you are not near 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, so make sure you’re always looking out for bells that you can use to reach new places. 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.

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:

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 each statue in Red.

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 with a secret chest inside. You can use Destiny 2 Opulent Keys to open similar looking chests while patrolling the Derelict Leviathan too.

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:

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 countered by the sheer quantity of enemies present. All sorts of Cabal foes will flood in 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:

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.

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.

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 on 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 find that there are four small platforms in the arena, two on the left wall and two on the right. War Beast and Chalice are on the left and right walls respectively and close to where players will arrive in the arena. Sun is on the left wall and Axe on the right, but they are at the far end of the arena towards the Bell of Conquest.

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:

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 reach the 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.

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:

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.

Destiny 2 tips | Destiny 2 Crucible tips | Destiny 2 Gambit tips | Destiny 2 Heroic Public Events | Best Destiny 2 Exotics | Destiny 2 Prime Engrams | Destiny 2 Adept mods | Destiny 2 The Witch Queen | Destiny 2 how to beat Savathun on Legendary difficulty | Destiny 2 Altars of Reflection puzzle | Destiny 2 faction chests for Trust Goes Both Ways | Destiny 2 Preservation mission | Destiny 2 Base Information challenge | Destiny 2 Defenses Down challenge

Will Sawyer is a freelance guides writer at GamesRadar+ who works with the rest of the guides team to give readers great information and advice on the best items, how to complete a particular challenge, or where to go in some of the biggest video games. Will joined the GameRadar+ team in August 2021 and has written about service titles, including Fortnite, Destiny 2, and Warzone, as well as some of the biggest releases like Halo Infinite, Forza Horizon 5, and Dying Light 2.

Get the best gaming deals, reviews, product advice, competitions, unmissable gaming news and more!

Thank you for signing up to GamesRadar+. You will receive a verification email shortly.

There was a problem. Please refresh the page and try again.

GamesRadar+ is part of Future US Inc, an international media group and leading digital publisher. Visit our corporate site (opens in new tab) .

© Future US, Inc. Full 7th Floor, 130 West 42nd Street, New York, NY 10036.