The Vaults of Borderlands 4 are never just about loot—they’re proving grounds, each guarded by a Primordial construct designed to test your skills. Among them, Primordial Guardian Radix is one of the toughest, combining brutal shock-based attacks with battlefield control that can overwhelm the unprepared. This guide covers how to unlock his Vault, break down his moveset, and use the right tactics to claim victory.
How to Unlock the Vault of Radix
Before you even face Radix, you’ll need all three Carcadia Burn Vault Key Fragments:
- Yawning Yard (Lopside Region): Hidden inside a corridor with a long dinner table.
- Wreck of the Last Great Hope (Tonnage Peel): Found by entering underground tunnels via a grappling hook door.
- Ruined Sumplands: Located near a body of water marked with golden orbs in the rock.
With the fragments in hand, travel to Grindstone of the Worthy in Carcadia Burn. A stone pillar will rise from the ground, letting you forge the fragments into a key. Insert it to reveal the Vault entrance, where Radix awaits.
Primordial Guardian Radix Overview
Radix is a massive Shock-element guardian with multiple health bars and phase transitions. His arena quickly becomes a hazard zone filled with rocks, lightning strikes, and roaming Pangolins—slow minions that are weak but can explode if triggered after death.
Key points before entering:
- Radix is always two levels above you, so his damage output scales with your level.
- His first health bar is shielded (blue)—best countered with Shock weapons.
- His later health bars are armor (green/yellow)—best countered with Corrosive damage.
- A shield with Shock resistance or immunity is highly recommended.
Radix’s Attack Patterns
Radix cycles between three combat modes—Regular, Drill, and Thunderstorm—each introducing new hazards. His attacks are heavily telegraphed, but they cover large areas, forcing constant movement.
Regular Mode
- Spinning Rocks: Stones float around Radix, blocking shots and occasionally hurled at you. Thrown rocks glow blue before launch—sidestep to avoid.
- Shockwave Pulses: Slams the ground to send waves across the arena. Jump or glide over them.
- Rock Spear & Jump Strike: Creates a spear and lunges, sometimes diving down to create a shockwave. Dodge sideways or run beneath him before impact.
- Stone Spikes: Blue patches on the ground warn of spikes about to erupt. Step aside immediately.
Drill Mode
- Leaping Drill Slam: Radix stabs down, releasing Shock mines. These mines detonate when approached—shoot them before they trap you.
- Underground Tunnel: Digs below and resurfaces with an AOE shock burst, leaving a trail of mines. Watch the ground trail to anticipate where he’ll emerge.
- Lightning Beam: Channels energy through his drill arm, firing a sweeping beam across the arena. Keep moving laterally.
Thunderstorm Mode
- Arena-wide Lightning: The entire battlefield darkens, and glowing blue patches indicate incoming strikes. Stay mobile and avoid clusters of blue zones.
- Stacked Hazards: This mode often overlaps with leftover mines and Pangolins, turning the arena into a minefield. Clear space whenever you can.
The Pangolin Factor
Throughout the fight, Flash Pangolins spawn endlessly. They’re weak, but they serve two purposes:
- Second Wind Safety Net: Keep a few low-HP Pangolins alive to use if you’re downed.
- Hazard After Death: If killed by Radix’s attacks, they leave spiked mines that detonate when approached. Don’t stand near their corpses.
Best Strategy to Defeat Radix
- Bring Shock and Corrosive Weapons
Start with Shock to strip his shields, then swap to Corrosive for his armor phases. DoT (damage-over-time) weapons help chip away while you dodge. - Control the Arena
- Use Radix’s own boulders as cover and platforms to escape shockwaves.
- Clear Shock mines regularly, prioritizing safe zones to move into during Thunderstorm Mode.
- Watch the Blue Indicators
Nearly every attack—spikes, lightning, thrown rocks—has a blue telegraph. Reading the floor is the key to survival. - Manage Mobility Wisely
Don’t burn your dash or glide charges too early. Save them for Drill Mode leaps or sudden lightning clusters. - Adapt Between Phases
- In Regular Mode, focus on consistent DPS while dodging rocks.
- In Drill Mode, kite Radix, clear mines, and punish him after his tunnel attacks.
- In Thunderstorm Mode, stay alert to overlapping hazards and prioritize survival over damage bursts.
Primordial Guardian Radix Loot Rewards
Defeating Radix grants both loot and progression rewards:
- Guaranteed Legendary Drops: Notable items include the Anarchy shotgun, Adrenaline Pump repkit, and class mods like Witch, Scientist, Grenazerker, and Forge Master.
- Vault Completion Bonuses: Expect red chests, Eridium, cash, and a Glide Pack upgrade that reduces stamina usage by 50%.
- Achievement: Beating Radix, alongside Inceptus and Origo, unlocks the Nothing Left to Guard achievement.
Radix isn’t a one-shot boss—his fight tests endurance, awareness, and patience more than raw damage output. By balancing mobility, clearing hazards, and exploiting elemental weaknesses, you can turn this stormy battlefield into one more Vault conquered.
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Stay sharp, watch for the blue signs, and Radix will eventually fall, leaving you with powerful loot and another step closer to mastering Borderlands 4. Play Now!
