How to Complete the Carcadia Burns Vault Guardian in Borderlands 4

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Vault hunting remains illegal in Borderlands 4, but most players just ignore the rules when the chance to loot Vaults and gain treasures is so tempting. A new Vault has appeared in the dry region of Carcadia Burns. Whether it’s your first or final Vault, you’ll need to overcome various challenges inside to claim your reward.

Access to the Vault isn’t free. You must first gather three Vault Key Fragments. To do that, capture the three Silos spread across the region, which reveal the general locations of the fragments on the map. The Silos are:

Rustical Hurl, located in the middle of Carcadia Burns.
Site Unseen, in the west.
Judgement’s Lapse, in the north.

Silos are special facilities controlled by the Order. They are claimed much like Safehouses, but without the need to find a datapad. Once captured, they act as fast travel points and reveal key locations on your map. After capturing each Silo, head to the indicated area and follow the on-screen indicator in the upper-right corner of your screen to locate the Vault Key Fragments. The closer you get, the more bars fill the indicator, and it emits noise and vibrations.

Vault Key Fragment One is located in the Lopside region, at the Rustical Hurl Silo in a canyon northeast of the Makeshift Chalet Safehouse. From there, maneuver around the rocks to find the fragment on the roof of small buildings at the western edge of the area.

Vault Key Fragment Two is in the Tonnage Peel region, near Site Unseen on a cliff at the western edge of the map, close to The Lowrise Safehouse. Access it by following the road south to Wreck of the Last Great Hope. Enter the tunnel beneath the site, which is filled with Creep and nests, and grapple off the red-lit alcove to find the fragment attached to a rock in the cave.

Vault Key Fragment Three is in the Ruined Sumplands, in mountains northwest of Carcadia, near The Marrow Narrows. From Judgement’s Lapse, head west then north, crossing the land bridge, and go northeast to the area near The Gunkworks. The fragment is in an alcove among gray stones and yellow gems by the riverbank.

Once all three fragments are collected, the Vault door appears on your map, located roughly in the center of the region. Search for it using the indicator, which vibrates and makes noise as you approach. The Vault is straightforward to find there, near Moxxi’s Bottoms Up! — just head south from the bar, jump onto the road below, and follow it east to the raised bridge. If you haven’t lowered it during the main mission, you can still jump onto the mechanisms and glide over. The Vault door will appear at the water’s edge as you get close.

Interact with the altar at the door to start the challenge named “Primordial Vault: Carcadia Burns,” then enter the Vault. Inside, you’ll face three combat arenas with checkpoints in between and a final boss fight against the Vault’s Guardian.

The first challenge involves fighting the Seneschal Order, an upgraded version of enemies from the Order, who are slightly tougher but attack with similar moves. In each arena, you’ll also confront a miniboss with unique abilities:

First miniboss: Stochastix, a judge-like Warden capable of spawning minor enemies and the Fabricator Witness.
Second miniboss: Crushing Depth, a heavily armored Hammerhead often accompanied by dangerous variants like Warheads.
Final miniboss: The Chisel, a powerful Domination Engine with an Ordonite Shield and aggressive leaping attacks. To damage it, shoot the purple-red crystals on its body to release Vile Ordonite Orbs, then destroy them to break the shield.

During battles, Radix shifts through three modes: Regular, Drill, and Thunderstorm, each with different attack patterns. Regular Mode includes spinning rocks, lightning strikes, metal fling attacks, and shock waves. Drill Mode involves jumping and tunneling underground, sending shock energy waves, and planting shock mines. Thunderstorm Mode unleashes widespread lightning strikes and increased aggression.

Radix always starts in Regular Mode. Dodge its rocks and energy waves, aiming at its face and legs for critical hits. Jump over energy waves or glide to avoid them. When Radix hits 60% on its shield, it switches to Drill Mode, making it more aggressive—destroy shock mines and use weapons with elemental damage (like Incendiary, Radioactive, or Corrosive) to whittle down its health. When its shield drops to 20%, Radix unleashes a massive energy wave, then reverts to Regular Mode until its shield is depleted. It then swaps to Drill Mode again at 50% health, and this cycle repeats, with Radix alternating modes every 30% loss in shield or health.

In Thunderstorm Mode, Radix becomes extremely dangerous, unleashing lightning strikes and dealing pure Shock damage. Stay close or just outside the arena’s middle ring to avoid lightning, and clear lingering Shock Mines and Pangolins that may still attack. Destroy shock mines proactively, especially when Radix transitions out of Drill Mode, to prevent devastating chain explosions.

As Radix nears 20% health, it switches back to Regular Mode, and once defeated, a rift appears. Interact with it to grapple into the final area or to exit the Vault. The victory rewards include an upgraded Glide Pack for reduced stamina use, along with two Red Chests, experience, money, Eridium, and a rare or epic sniper rifle. Completing the side mission unlocks the “Nothing Left To Guard” achievement if the other Guardians, Inceptus and Origo, have also been defeated. Afterward, you can grapple into the next rift to leave or restart the fight with Radix at Moxxi’s Big Encore.