Once you reach the deepest section of the bunker, you'll enter a massive circular chamber lined with power conduits and glowing machinery. The room locks down as the fight begins, and the Core Observer descends from Borderlands 4 Boosting above, scanning the area for intruders-you.

How to Defeat the Core Observer

At first glance, the Core Observer might seem like just another oversized drone-but underestimate it, and you'll quickly find yourself overwhelmed. The boss constantly summons smaller drones throughout the fight, each type dealing different kinds of elemental damage. Here's how to handle the encounter efficiently:

1. Manage the Ads

The Core Observer regularly spawns multiple "Corroborating Witnesses," smaller drones that come in Cryogenic (ice) and Radioactive (radiation) variants. These can chip away at your shields and health if left unchecked.

While their individual damage isn't high, their numbers make them dangerous. Use area-of-effect weapons like Torgue launchers or splash-damage grenades to clear them quickly. If you get downed, these minions also provide good Second Wind opportunities-so keep one alive if you need an emergency revive.

2. Target the Correct Weak Points

Unlike many other drone bosses, the Core Observer's critical weak spot isn't its eye. Instead, its underbelly serves as its true critical hit location. To expose it, bait the drone into hovering low or wait for it to pause mid-attack.

Aim your shots there with precision weapons like sniper rifles or Jakobs assault rifles for massive critical hits. Elemental weapons will further amplify your damage when paired with the right effects.

3. Use the Right Elements

The Core Observer has two distinct health bars-one green (armor) and one blue (shields). Matching your weapons to each phase is key:

Green Bar (Armor) → Use Corrosive weapons to melt through quickly.

Blue Bar (Shields) → Switch to Shock weapons once the armor is gone.

Elemental matching dramatically shortens the fight. If you have a weapon that can swap elements (like a Maliwan hybrid gun), this phase transition becomes much smoother.

4. Movement and Cover

The arena is circular with several raised platforms and energy conduits for cover. Keep moving clockwise or counterclockwise to avoid getting cornered. The Core Observer uses laser bursts and orb projectiles that can track your position. Strafe frequently and duck behind cover between attack waves.

If you're playing as a character with mobility abilities (like dash, teleport, or clone swaps), use them to reposition after each drone wave.

5. Team Coordination (for Co-op)

In co-op mode, communication is key. Assign one player to handle additional control while another focuses on the boss's weak point. Having someone with healing or barrier abilities (like Zane's Barrier or Amara's Sustainment builds from earlier games) helps mitigate the constant chip damage from the drones.

Farming Core Observer for Legendary Loot

Once defeated, the Core Observer has a chance to drop several high-value Legendary Borderlands 4 Items. While the drop pool can vary slightly between patches, here's what's known so far:

Known Legendary Drops

Ion Scythe (Legendary SMG) – A Hyperion submachine gun that fires a steady beam instead of bullets. Gains damage as you maintain fire on the same target-perfect for sustained fights like this one.

Watcher's Core (Legendary Shield) – A reactive shield that releases shock pulses whenever your shields recharge, dealing area damage to cheap Borderlands 4 Boost nearby enemies.