Borderlands 4 Teen Witch Siren mod — effect, boss, and fast farm

Teen Witch at a glance

What the Teen Witch mod actually changes

Teen Witch turns Vex’s lifesteal into a true sustain loop. Hitting enemies at full Health spills some of that leech into your Shield, keeping it topped without relying on passive recharge. If your Shield is already maxed, lifesteal goes further and creates Overshield. In practice, this lets you stay aggressive through chip damage, maintain Shield‑based bonuses more reliably, and recover quickly after taking a hit.

Because you can actively replenish Shield through damage, the mod pairs well with high‑uptime gunplay, Vex’s own lifesteal skills, and Shield parts or perks that reward having charge available (for example, amp effects that consume Shield per shot).

How to unlock the Arch of Radix Vault

• Collect the three Vault Key Fragments scattered in Carcadia Burn.

• Use them to open the Arch of Radix Vault entrance in the same zone.

• Enter the Vault and fight your way to Primordial Guardian Radix.

Once the Vault is open on a character, you can re-enter to farm the boss any time.

Fast farm loop for Radix (Teen Witch’s dedicated drop)

• Fast travel to Rustical Hurl (Silo) in Carcadia Burn.

• Head into the Arch of Radix Vault and clear to the arena.
• Use the Moxxi’s Big Encore machine at the arena entrance to restart the encounter for repeat attempts.

• Defeat Radix, check drops, and immediately trigger another encore run.

Drop rates are on the stingy side and Class Mods aren’t restricted to your current Vault Hunter, so expect to see pieces for other characters during the grind. Radix remains the most consistent path to Teen Witch, with occasional world drops possible from the general legendary Class Mod pool.

Why Teen Witch is strong on Vex (and how to build around it)

• Shield uptime while pushing damage: lifesteal into Shield keeps you firing instead of kiting for recharge.
• Overshield padding: when your Shield is full, lifesteal builds an overshield buffer so you can face-tank brief bursts.
• Synergy with Shields that trade charge for power: amp-style effects are easier to sustain when shots immediately restore Shield through lifesteal.
• Skill synergy: Vex’s lifesteal passives compound the mod’s effect, and continuous fire from strong kinetic shotguns makes the sustain feel nearly constant.

Practical pairing that plays to the mod’s strengths: a high-damage kinetic shotgun for reliable lifesteal procs, plus a Shield with an amp modifier so the restored charge translates into per-shot damage. With this setup, you burn Shield to boost damage and instantly recover it by landing hits.

Teen Witch boosted skills

Teen Witch can roll bonus points into Vex skills. The pool includes:

• Conjunction
• Blood Is Magic
• Corporeal
• Grave Thirst

Check your roll and redistribute points to take advantage of the extra ranks the mod provides.

Troubleshooting the farm

• Seeing other characters’ mods: this is normal behavior; Class Mods aren’t weighted to your active Vault Hunter.
• Long dry spells: keep runs short and consistent. Use the encore device at the arena so you’re spending time on boss kills, not travel.
• Level targeting: farm at your current endgame level so the drop stays viable for late-game activities.

The short version: open the Arch of Radix by finishing Carcadia Burn’s Vault Fragments, then loop Radix from Rustical Hurl using the arena’s encore machine. Teen Witch’s lifesteal-to-Shield conversion makes Vex’s sustain feel effortless—especially with a damage-forward shotgun and an amp Shield that benefits from the charge you’re constantly restoring.