menu
MobalyticsUse your favourite features in-game with our Desktop App
Borderlands 4 Guide

Leader Willem Boss Guide & Legendary Loot

Beginner
Late Game
Bosses
Updated on Dec 17, 2025
Dec 17, 2025

Overview

Leader Willem is a Order-tech enhanced human optional boss located The Excrucible Order warehouse.

In order to unlock him as a killable boss, you must complete a side quest starting with Enter the Electii and ending in The Mole's Gambit. This quest chain is located in Carcadia Burn and requires finishing the zone's story mission to complete.

If you're hunting for the best legendary weapons, check out our page here for more info!

Leader Willem


Drops

Item

Type

Details

Rainbow Vomit

Shotgun

Shoots droplets of 3 different elements

Zipper

Pistol

Grants +75% Critical Damage and +75% Damage when hitting a target in the back

Firepot

Grenade Ordnance

Spawns homing Torgue stickies over time

Location

  • Progress through the story until reaching "Enter the Electi" a Side Quest in Carcadia Burn area.
  • Complete the Side Quest to its completion
  • You will encounter Leader Willem

Tips & Tricks

  • Leader Willem has a blue (Shield) and a yellow (Armor) healthbar, making him first vulnerable to ⚡Shock and ☢️Radiation, and then 🟢Corrosive and ❄️Cryo.
  • The boss does heavy elemental damage (can be any element).
  • Almost all of his abilities can be dodged or out-ranged.
  • There are plenty of obstacles that can be used to block many of his attacks, however the truck located to the left as you enter the arena will give you great cover while not block you into a corner.
  • In the second phase of the fight he will consistently spew his element in a nearby area around him - more reason to keep away!
  • There is a severe lack of adds in this fight, making Kill Skills ineffective.

Table of Contents

Latest Guides

BL4 Theorycrafting Resource Hub
By GIRTHQUAKE Updated on Mar 16, 2026
Mechanics
Late Game
Beginner
+1
Mechanics
Late Game
Beginner
Discussion
Borderlands 4: C4SH Overview
By Mobalytics Updated on Mar 16, 2026
Weapons
Beginner
Vault Hunters
+1
Weapons
Beginner
Vault Hunters
News
Vex's Damage Formulas
By Ratore Updated on Mar 16, 2026
Late Game
Vault Hunters
Mechanics
Late Game
Vault Hunters
Mechanics
How To Easily Beat The Stone Demon Boss on Every Character
By Ratore Updated on Mar 15, 2026
Weapons
Shields
Late Game
+3
Weapons
Shields
Late Game
Vault Hunters
Mechanics
+1