Borderlands 4: How to Unlock the Secret Vulkorr Boss (Flip the Switch)

Vulkorr is not on any mission board. The fight only exists if you go looking for five power switches scattered around Providence Island, and the game does almost nothing to tell you where they are. Flip all five and a signal lights up on your map that leads straight into the arena.

Quick answer: Flip all five Substation Switches on Providence Island — one in Vinechoked Canopy, two in Bagheera Range, two in Pyroclast Field — then head to the Substation Control marker that appears in Bagheera Range and kill Vulkorr inside.

What the Flip the Switch challenge tracks

Open your Challenges menu and look under FL4K and the Last Resort. The entry is called Flip the Switch, and its description spells out the goal in one line: “Flip all Substation Switches to activate a signal you can track on your map.” The counter goes to five, and each switch is logged as a collectible tied to Providence Island.

Challenges menu with Flip the Switch selected under FL4K and the Last Resort, showing switch progress — The Flip the Switch challenge sits under FL4K and the Last Resort and counts your Substation Switches.

That counter is your progress bar for the whole thing. Nothing appears on the map until it reads 5 of 5, so use it to check which switches you have already banked before you go hunting again.

All five Substation Switch locations

Every switch sits behind a small physical lock — a battery, a wire, a wall, or a room full of enemies. Here is the short version before the walkthrough.

Switch	Area	What blocks it
1	Vinechoked Canopy	Battery above the door, console outside
2	Bagheera Range (north)	Hanging green battery you shoot
3	Bagheera Range (south)	Red floor wire leading to a button
4	Pyroclast Field (east)	Enemies inside Tediore Supply Outpost Primaria
5	Pyroclast Field (south)	Wall you climb to reach a generator

How to flip each Substation Switch

In Vinechoked Canopy, find the sealed building and look up — a battery sits on the ledge above the entrance door. Grab it, drop down, and slot it into the console on the outside wall. The door opens, and the switch is waiting inside.

Move to the northern part of Bagheera Range. A glowing green battery hangs near the entrance to the building — shoot it, and the door unlocks. Clear the enemies inside before you walk up to the switch.

Firefight in Bagheera Range with loot and XP pickups dropping around the player — Clearing the defenders at the northern Bagheera Range switch building.

Head south in the same region for the third switch. There is a red wire running along the floor — follow it to the generator button at the end, press it, and the door opens. Drop down into the room below and flip the switch there.

Player firing a full-auto weapon at a Tropical Creep in southern Bagheera Range — Wildlife such as the Tropical Creep gets in the way while you trace the red wire in southern Bagheera Range.

Travel east in Pyroclast Field to Tediore Supply Outpost Primaria. This one has no puzzle at all — push inside, kill the Badass Purgon and the rest of the room, then flip the switch.

Entering the industrial corridor at Tediore Supply Outpost Primaria in Pyroclast Field — The fourth switch is inside Tediore Supply Outpost Primaria in eastern Pyroclast Field.

Finish in southern Pyroclast Field. Jump over the wall beside the structure to reach a generator and press its button, then come back around to the main room and flip the last switch.

Player aiming at a floor-mounted generator machine in southern Pyroclast Field — The generator behind the wall in southern Pyroclast Field powers the final switch.

Where Substation Control appears on the map

With the fifth switch flipped, a yellow search circle drops onto the map in Bagheera Range, labelled as a Substation Control Hint Area with the line “A hidden power source is somewhere in this area.” Fast travel to the nearest point and sweep the circle until the Substation Control entrance resolves into a real marker.

The map entry for the location keeps the mystery going with the note “Find all the switches, but what do they open? What lies inside?” Walk in and the arena seals behind you for the fight.

Vulkorr rewards and how to confirm the unlock

Vulkorr is a straight boss encounter inside Substation Control. When it dies, you get a Substation Boss Defeated confirmation on screen, the Substation Satisfaction trophy pops, and legendary loot hits the floor — including the Evanescent Avarice assault rifle.

Note: sweep the arena for drops before you leave. The Evanescent Avarice is the headline reward, but the kill spills a pile of gear alongside it.

If the Substation Control marker never shows up

There is really only one failure state here. If the search circle has not appeared in Bagheera Range, the Flip the Switch challenge is still short of five, so go back to the Challenges menu and compare the counter against the five locations above. Reaching a switch room is not enough either — the challenge only ticks when you interact with the switch itself, so double-check the two Pyroclast Field rooms where it is easy to clear the enemies and walk straight back out.

Done in order, the whole run takes a few minutes of travel between Vinechoked Canopy, Bagheera Range, and Pyroclast Field, and the reward is a boss most players never see.