Here’s a guide to the best bosses to farm in Borderlands 4 — their locations, what loot / legendaries they drop, how hard they are, and when it’s good to farm them.
What to know
- Moxxi’s Big Encore Machine lets you respawn defeated bosses for cash, enabling targeted farming without save-quitting.
- Early bosses like Splashzone and Oppressor offer the best starter legendaries, with dedicated drops like the Swarm grenade and throwing knives.
- Rift events and Ripper Drill Sites provide bonus loot opportunities alongside boss runs for efficient grinding.
- Weekly Big Encore variants increase legendary drop rates but cost more, ideal for endgame progression.
Boss by boss breakdown
| Boss | Location / Mission | Notable Loot | Difficulty & Farming Tips |
|---|---|---|---|
| Splashzone | Riptide Grotto, Fadefields — mission Recruitment Drive | Lead Balloon (Shotgun), Firewerks (Shield), Jelly (Grenade) | Great early farm. Weak to Incendiary. Easy access, quick kills, perfect for first legendaries. |
| The Oppressor | The Killing Floors, Fadefields — mission A Lot to Process | Asher’s Rise (Sniper), Onslaught (SMG), Blood Analyzer (Repkit), Streamer (Heavy) | Mid-early game. Airborne phases make it trickier. Weak to Shock and Corrosive. Requires precision. |
| Bio-Bulkhead | Synthetic Nave, Fadefields — mission Down and Outbound | Waterfall, Budget Deity, Sho Kunai | Bulky tank-type. Requires sustained damage. Drops solid legendaries. Good once you’re mid-leveled. |
| Idolator Sol | Fortress Indomita, Fadefields — mission Rush the Gate | Goremaster, Golden God, Onslaught, class mods (Bio-Robot, Technomancer, Furnace) | First big hurdle. Multi-phase, immunity mechanics. Longer farm but very rewarding. |
| Horace | Hungering Plain, Fadefields — mission Recruitment Drive | Aegon’s Dream, Pacemaker, Lucky Clover | Early-mid option. Less farm-efficient than Splashzone but still drops useful legendaries. |
| Sludgemaw | Watershed Gate, Fadefields — side mission All Charged Up | Birt’s Bees (SMG), Kickballer (Shotgun), Onion (Shield) | Side boss with fun loot. Position carefully to avoid being swarmed. Good shield farm. |
| Primordial Guardian Inceptus | Arch of Inceptus, Fadefields — mission Rush the Gate | Husky Friend, Extra Medium, Ravenfire, Elementalist, Filantropo, Avatar | Heavy guardian fight. Long HP pool. Great loot variety but slower kills. |
| Callous Harbringer of Annihilating Death | Terminus Range, Craven’s Nook bunker | Hot Slugger, Atling Gun, Kaleidosplode | Brutal late-game fight. Expect high damage. Not ideal early, excellent endgame farm. |
| Callis, the Ripper Queen | Carcadia Burn, Moon-Called Throne — mission Queen’s Rest | Queen’s Rest, Pandoran Memento, Viking, Esgrimidor, Skeptic, Illusionist | One of the hardest bosses. Aggressive and relentless. Great loot pool for endgame builds. |
Who to farm when: early vs later
Here’s a rough ordering/priority for farming bosses, depending on your stage in the game and what you want (XP, legendaries, speed):
- Very early game/Level ~4-10:
- Splashzone is the go-to. Easy, fast, good drop chances.
- Then maybe Horace, The Oppressor, once your build is decent.
- Mid game (after you’ve done several main missions, maybe level ~15-25):
- Idolator Sol, Bio-Bulkhead, Primordial Guardian Inceptus. These give more powerful legendaries and class mods, but the fights are heavier or more complex.
- Sludgemaw is a decent side-boss for extra legendary variety.
- Late game/end of Fadefields into Carcadia Burn and beyond:
- Callous Harbringer, Callis the Ripper Queen, etc. They become better in loot power, maybe special gear, but are tougher.
- For fastest early legendaries, Splashzone is your best bet.
- If you can handle more mechanics, Idolator Sol is a very good boss for legendaries and mods.
- Sludgemaw is good for variety (especially shields, shotguns) without being overwhelming.
- The toughest are later bosses like Callous Harbringer / Callis the Ripper Queen, etc., but they also give the most reward (if you’re ready).
Which bosses are toughest
- Idolator Sol gives you a first real skill check with phases and immunity mechanics.
- Primordial Guardian Inceptus and Callous Harbringer are endurance fights with massive health.
- Callis, the Ripper Queen is the hardest, with aggressive phases and devastating damage.
How boss prowess evolves
As you progress, bosses steadily demand more:
- Health and shields balloon, making DPS checks critical.
- Elemental weaknesses matter more, punishing mismatched gear.
- Mechanics shift from simple arenas to multi-phase gauntlets.
- Loot rewards improve dramatically, with high-end bosses dropping class mods, rare legendaries, and unique shields.
If you’re starting fresh, Splashzone is your best early farm. By mid-game, Idolator Sol offers top-tier rewards. For endgame loot hunters, Callous Harbringer and Callis the Ripper Queen stand as the ultimate tests of power and farming endurance.
