The Great Vault is a main mission that begins in Pandora in Borderlands 3.
Your task is to stop Troy from destroying Pandora by awakening the Destroyer.
Here’s a walkthrough of The Great Vault in Borderlands 3.
This mission is recommended for level 29 and above.
Speak to Lilith
Your first objective is to head back to Sanctuary.
Meet Lilith at the bridge.
Look out the window
You’ll get another transmission from the twins. This time, Troy uses his Siren powers against the moon.
Say goodbyes (optional)
This part is optional, you can say your goodbye to almost everyone including Marcus, Ellie, Zer0, Ava and many more.
Most of them won’t give you anything, and those that do give, mostly hand out nonsense.
Like this guy Marcus who only gives one pack of free ammo. It’s probably a joke.
If you go to Moxxi though, she’ll ask you to try the slots and you’ll win a weapon.
The rest are mostly useless items. Hammerlock only gives a pistol.
Once you’re ready to proceed, talk to Lilith.
Head to Roland’s Rest
Go to Roland’s Rest to join the allies in making an attack on the COVs.
Talk to Vaughn
Speak with Vaughn who’s waiting for you.
Catch up to Tannis
Grab a vehicle and catch up to Tannis. She teleported there using her powers.
Clear out COV
Once you’re at the entrance, take out all the COV. You’ll be joined by allies.
Speak to Tannis at the rooftop area.
Drive to the Cathedral of the Twin Gods
Grab your vehicle and head to the Cathedral of the Twin Gods.
You can enter with the vehicle.
Go all the way to the end.
You don’t need to stop to kill the enemies. Just drive all the way.
At the entrance of the building, follow Ava on foot. There’ll be Atlas soldiers with you as well.
Ava will plant a bomb. Shoot at the bomb for it to explode.
Clear outer defenses
You’ll need to clear the outer defenses first.
Fight to Courtyard of the Damned
Head towards the courtyard on your own.
Clear out all the enemies along the way.
Open sanctum door
At the courtyard, fight your way up to the control area.
Open the sanctum door.
Enter inner sanctum
Once the door is open, more enemies will come out. Get rid of them.
Enter the inner sanctum.
Go towards the end and you’ll face the Anointed. Take him out.
Raise processing tank pressure
Next, you’ll need to raise the tank pressure by turning the valves. The location of all 4 valves are shown in the map.
The first two valves are on the ground and are easily accessible.
After you turn the first two valves, two more Anointed soldiers will appear. Kill them first.
Once the area is secure, you need to turn the other 2 valves. Both of them are located at the top, one on the left and the other on the right side.
To get to the top, you’ll need to go either to the left or right first.
There’ll be two enemies on each side.
Once you’ve turned one valve, head towards the other side to turn the other valve.
Destroy processing tank
After 4 valves are turned, destroy the processing tank in the middle.
Jump into pipe
When you’re ready, jump down into the pipe.
Head to The Great Vault.
You’ll need to go all the way to find Troy.
Defeat Troy (boss)
Finally, you’ll get to fight Troy.
The battle is pretty tough although his HP isn’t too high. It’s difficult because he can kill you in 1 hit.
If you get hit by any of those energy orbs, you’ll be incapacitated. Similarly, he can glide towards you and take you down in 1 hit.
Either way, you’ll probably repeat the fight many times.
If you do get into the “fight for your life” mode from getting hit by the orbs or whatnot, you need to immediately try to get second wind before you die.
Kill any of those regular mobs.
If you can’t find those Tinks to kill, look up in the sky. There may be bird creatures to kill and get second wind.
I don’t know of any regular way to not die immediately from those orbs, but if you’re Moze, the Iron Bear can withstand a couple of hits at least.
It’s mostly about reflexes and it’s especially important in this fight.
Troy also pairs up with Tyreen during the fight to create energy attacks from the ground. Avoid those glowing yellow energy balls (indicator) and you should be safe.
He also uses a wall of eridian energy. If you get caught in it, you’ll probably get incapacitated as well.
Don’t stand too far out and you’ll be safe.
Troy can also create a giant rock-like arm and slam it on the ground. Just run around to avoid it.
The easiest way to clear this boss battle is by joining a group.
That way, if some die, the boss fight will not restart as long as there are members still living in the arena.
Investigate ECHO device
Once Troy dies, pick up the ECHO device.
Talk to Lilith
Speak with Lilith.
Next, the vault door will open. Loot the vault.
Pick up the Eridian Analyzer inside the vault. There’ll be other regular loot as well.
Talk to Tannis
Go back out from the vault and speak with Tannis.
The mission completes here. You’ll earn cash and get an item as reward.