What to know
- Callous Harbinger of Annihilating Death is a boss inside Craven’s Nook Order Bunker in the Terminus Range, Heart of the Mountain.
- The boss drops the legendary Jakobs shotgun Hot Slugger, plus other legendary items like Atling Gun.
- Entry to Craven’s Nook requires destroying an armored door using a Locust Canister or interacting with a vent mechanism.
- The fight involves dodging shockwaves, missile barrages, charge attacks, and projectile hell; keep moving and use cover.
The Callous Harbinger of Annihilating Death is known for being a tough but manageable boss fight in Borderlands 4, rewarding players with the sought-after Hot Slugger shotgun. Found deep inside Craven’s Nook, a bunker in the Terminus Range area, this boss fight marks an important challenge that can be farmed repeatedly for legendary drops once unlocked.
Location of Callous Harbinger of Annihilating Death, and how to reach him
Callous resides inside the Craven’s Nook Order Bunker, located in the Terminus Range, specifically the Heart of the Mountain region, sometimes referred to as Bones of Sanctuary. This area unlocks after progressing through the main campaign, roughly after the mission "One Fell Swoop."
To gain entry to the bunker:
Step 1
Approach the bunker door, which is armored and inaccessible by normal means.
Step 2
Look for a Locust Canister dispenser or a similar explosive device on a ledge or rock near the entrance.
Step 3
Grab a canister and throw it at the door to destroy it, or if the bunker uses a vent mechanism, pull the vent lever nearby to open it.
Step 4
Proceed through the bunker, clearing waves of Order enemies in multiple rooms.
Step 5
Use grapples and elevators inside to advance until reaching Callous’s arena.
How to fight Callous Harbinger of Annihilating Death [step-by-step guide]
Prepare well for the fight
Ensure your character is at an appropriate level (recommended 30-50+) and equip weapons effective against Shock, Corrosive, or Cryo, as these are the boss’s weaknesses.
Dodging Callous’s slam shockwave
Callous repeatedly slams the ground, sending a shockwave across the arena. Time jumps to avoid damage.
Avoid charge attacks
Sometimes, Callous will charge with his shield lowered. Dash to the side quickly to evade and counterattack.
Take cover from missile barrages
When Callous’s shield glows, brace for a missile attack. Quickly move behind elevated platforms or cover to avoid damage.
Survive diamond bullet hell
Callous may fire diamond-shaped projectiles in all directions. Hide behind cover to stay safe and wait for an opening.
Kill the boss
When Callous’s shield is down, focus fire while maintaining mobility to reduce the chances of being hit.
Loot drops from Callous Harbinger of Annihilating Death
| Item Name | Type | Notes |
|---|---|---|
| Hot Slugger | Legendary Jakobs Shotgun | Key drop; grants damage stacking on kills (+30% per kill, up to 3 stacks) |
| Atling Gun | Legendary Heavy Weapon | Another notable drop from the boss |
| Kaleidosplode | Legendary Weapon | Also in the drop pool |
The Hot Slugger shotgun is prized for its slow but heavy slug shot and +30% damage stacking effect that lasts 10 seconds per kill, making it excellent for burst damage and boss fights. It also ricochets critical hits to nearby enemies.
Combat tips to defeat Callous effectively
- Stay mobile throughout the fight; constant movement avoids most attacks.
- Use shock or corrosive weapons to exploit elemental weaknesses.
- Jump over shockwave slams rather than trying to tank them.
- Take cover for missile and projectile phases.
- Dash sideways to evade charges.
- Aim for critical hits to maximize damage and trigger shotgun ricochets.
- Manage adds if spawned, but prioritize boss damage.
- Use area control and burst damage to shorten fight duration.
Why farm Callous Harbinger of Annihilating Death repeatedly
The Hot Slugger is a high-value Jakobs legendary with the stacking Blazing Barrel damage buff on kills — ideal for builds that chain kills for sustained damage bursts. That perk alone makes Callous one of the more sought-after farm bosses for shotgun-focused or crit-ricochet builds. The boss is short and repeatable: once you’ve unlocked the bunker, the run is compact and efficient for targeted farming sessions.
Is Callous Harbinger of Annihilating Death an essential quest?
Facing Callous is an essential challenge in Borderlands 4 for those pursuing top-tier legendary weapons. The fight is a balanced mix of pattern recognition and mobility, rewarding players who keep their wits and dodging skills sharp. Though the boss's name sounds intimidating, mastering Callous unlocks a powerful shotgun and other loot critical for late-game success.
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