I just got done with the solo flawless run, after much trial and error, so I thought I'd share some tips and strategies while it's still fresh. For the purposes of this post, I'm going to assume that you understand the mechanics of bells, Bellkeepers and Standards; if you don't, there are plenty of guides that will get you up to speed. I won't go too deep into the details of my subclass, as each class will have to play differently in the general loop of staying alive. These are just tips I have for dealing with the mechanics throughout. [b]Nightmare of Gahlran[/b] Extended damage window without use of a glitch or cheese - when you first enter the Nightmare Realm, kill both Standard Bearers [i]but only pick up one Standard[/i]. Proceed as normal, clear out one side-room of Shades and then pick up the second Standard on your way out - [b]do not kill the Standard Bearer[/b] this time. Again, proceed as normal. Now, when you clear out the second room of Shades, the Standard Bearer will be in the room with you. Killing it will grant you an extra 15 seconds in which to do damage. Ignore the Standard that it drops, as it will not actually function properly in the "real" world. Glaive of Dreams - if you are so inclined, you can equip this mod and use a Glaive in this encounter. The Shades drop Unstable Essence when killed, and the buff they provide does work against the boss. Normally, the timer doesn't give you much to work with before it expires, but the mod extends this timer to 30 seconds on pickup and therefore has a sizeable impact on your boss damage. I didn't actually use it, but I definitely could have done with great ease - have the mod on at all times and swap to a Glaive before you enter the second side room. What did I use? Witherhoard, Funnelweb, Falling Guillotine, Starfire Protocol with the normal Fusion spam build. Note that the grenades are responsible for the bulk of the damage, not the Sword. Prioritise throwing them rather than slashing, if you copy this. [b]The Vault[/b] Bellkeeper placement - when possible, stand in the area that has a Standard which you need and shoot the bell [i]on the opposite side of the room[/i]. This causes the Bellkeepers to spawn right next to you. Kill them ASAP, so you don't have to worry about the bell being closed. Top of the stairs - in the "real" world, the top of the large-ish staircase is your safe space. The minibosses can't come up there (the third one can when doing a particular melee attack, but it will immediately retreat after doing this) and the Legionaries only come up in ones and twos, making them easy to deal with. What did I use? Deliverance, Tarrabah, Corrective Measure, same build as before. Machine Guns are phenomenal in this encounter, especially if you have one with a reload perk. They will clean out the areas where the Standard Bearers spawn in no time, and are also very effective for killing Bellkeepers in quick fashion. Tarrabah was also amazing for that same thing, Ravenous Beast has a stupidly high uptime because of how many enemies there are and it repays that in kind. [b]Nightmare of Caiatl[/b] Prevent enemies from spawning in the real world - https://www.youtube.com/watch?v=-6LgEbgOQZ8 Much better explanation than I can provide, means that the only enemies you have to deal with are the boss and the Bellkeepers. Incendior packs - if you see an Incendior backpack on the ground, shoot it until it explodes. Enemies can't target them, but they can most certainly hit them while aiming for you. If one blows up under your feet, that usually means instant death. Do your due diligence by shooting them or, better yet, use a Fusion Rifle against Bellkeepers; this disintegrates them, which means the backpacks will never drop on the ground. Collecting standards - stand on a balcony where a Standard Bearer would spawn before shooting a bell. Teleport in and immediately kill the enemy to get the time extension. Then, move straight onto the main platform and work on killing the Bellkeepers. It might sound dangerous, but it's often best to ignore the Colossus at each end; they take a good amount of time and/or ammo to kill, both of which are at a premium. With all Bellkeepers dead, you can make a judgment call as to whether or not you should attempt to collect a second Standard or just leave. Getting the damage phase right - shoot a crystal on a chain, go to the bottom of the stairs next to where Caiatl spawns and then face the middle bell. As soon as you get teleported in, kill both middle Bellkeepers. Look at Caiatl to see which direction she is going in - if she goes left or right, go near her and bait a melee attack from her. Use this time to kill the appropriate Bellkeepers. If you aren't 100% confident you can do it in time, don't try - losing a damage phase is much better than trying to get it and dying. When moving between bells, try to kill the Psion snipers and even position yourself such that some of them can't shoot you. What did I use? Fatebringer, Glacioclasm, Lament. Glacioclasm was the star here. My roll has Subsistence and Reservoir Burst, which means that it was great at clearing enemies in the Nightmare Realm and it could chain one-shots on the Bellkeepers while also disintegrating their backpacks. Lament isn't the #1 top DPS weapon here, but it is absolutely the safest. The health return on hit goes beyond invaluable. For those who aren't aware, the most efficient combo is 2 charged light attacks, 1 charged heavy then 2 regular light attacks, then repeat. With Lucent Blade and its extra perk of faster Sword energy recharge, I killed the boss in a respectable 4 phases, including a missed bell or two. This is a big wall of text, so good job on making it to the end. If there are any questions or you're looking for help, I'll be happy to answer to the best of my capabilities. Good luck!