Vault Rewards, as named by the Achievements, are unique Eridian tools found within the Vaults of Borderlands 3. Gameplay wise, they act as progression mechanics that allow the character to access certain side items that were previously inaccessible.

Types

Eridian Resonator

• It pulses and seems to sing in your mind: "Start smashing stuff..."

The Eridian Resonator is found in the Vault of the Rampager, during the story mission Beneath the Meridian. It allows the wielder to smash eridium crystals throughout the galaxy with their melee attack. This can also be used to shatter the crystals on Eridium chests, allowing the character to loot its contents. On modernized locations like Promethea or The Handsome Jackpot, the Eridian Resonator can be used to smash purple cylindrical containers for eridium.

An Eridium Crystal.

An Eridium Container.

An Eridian Chest, covered in crystals.

The same chest without crystals.

Eridian Synchronizer

• Attunes your mind to the power of Eridian Artifacts. You know what that means? Stat boosts!

The Eridian Synchronizer is found in the Vault of the Graveward, during the story mission Cold as the Grave. It allows the character to equip Eridian Artifacts.

Eridian Analyzer

• Another ancient and mysterious Eridian device that unlocks the ability to decipher the Eridian language. And it probably won't give you brain damage either.

The Eridian Analyzer is found in The Great Vault, during the story mission of the same name. It unlocks the ability to decipher Eridian Slabs, which provides backstory of the Eridians and Sirens as told by the Siren Nyriad.

Eridian Fabricator

The Eridian Fabricator is found during Footsteps of Giants, in the Vault of the Serpent located in Tazendeer Ruins. Unlike other Vault Rewards, it is not guarded by a Vault Monster (Typhon DeLeon killed The Serpent prior to the events of the game), and is not a permanent upgrade, as the Eridian Fabricator is technically considered as a weapon. The Eridian Fabricator is capable of launching random weapons at the cost of some eridium.

Eridian Ascensionator

• Opens up new shards of reality where everything is extra super crazy. Enjoy the mayhem!

The Eridian Ascensionator is found in the Vault during the story mission Divine Retribution. It unlocks Mayhem Mode, which can be changed onboard Sanctuary III.

Notes

• Vault Rewards are tied to each character save file. Creating a new character after using one that has the rewards will require it to be unlocked again.