The borderlands 4 stone demon is the late-game elemental gate boss in the Ashen Spires region. It is the first fight in the game where bringing the wrong element type results in a hard wall, not just a slow kill. We are an unofficial fan site, and this walkthrough is verified against Patch 1.4 (2026-04-22) on PC.
Region: Ashen Spires, eastern caldera
Level range: Lv 38-42 (scales above 40)
Recommended Vault Hunter: Vex, elemental tree
Estimated time: 6-10 minutes first clear
How to start
The borderlands 4 stone demon arena unlocks after you complete two prerequisites: the side mission “Ash and Echo” and reaching at least Vault Hunter level 36. Once both are done, an ECHO from Lilith plays the moment you fast-travel to Spires Plateau. Drive northeast along the magma vein road for about 90 seconds, dismount at the rune-lit gate, and walk in. The arena fight starts on a short timer (~8 seconds) once you cross the threshold, so weapon-swap to your fire loadout before stepping in.
Step-by-step walkthrough
- Pre-fight prep. At the rune gate, hit the small forge altar to refill ammo and shield. This is free and the only altar in the area — use it.
- Phase 1 — Stone (100 to 75 percent HP). The demon is encased in cracked stone. Only fire damage breaks the shell. Aim for the chest crack, not the head; the head is a damage decoy in this phase.
- Phase 2 — Magma (75 to 40 percent HP). Shell breaks, magma exposed. Switch to cryo. The arena floor heats up and you take damage outside the cooled circles — stay near the geyser vents.
- Phase 3 — Ash (40 to 0 percent HP). The demon shifts to ash form, becomes faster, and gains a teleport. Switch to shock. Critical spot moves to the spine when its back turns during teleport recovery (~1.5 second window).
- Loot phase. It drops in place; the Demon Heart relic spawns about 4 meters behind the corpse, easy to miss.
Boss mechanics: weakness rotation
| Phase | HP range | Weakness | Resists |
|---|---|---|---|
| Stone | 100-75 percent | Fire | Cryo, kinetic |
| Magma | 75-40 percent | Cryo | Fire (heals it!) |
| Ash | 40-0 percent | Shock | Cryo |
Bringing fire into phase 2 actively heals the borderlands 4 stone demon. This is the #1 reason first-time runs wipe.
Recommended build
- Vault Hunter: Vex, elemental synergy tree
- Primary: Fire assault rifle with high mag size
- Secondary: Cryo SMG or pistol for phase 2
- Tertiary: Shock shotgun for the final phase (or use Petrified Maw on subsequent farms)
- Class mod: Element swap cooldown reduction
- Action skill: Anything that grants brief invulnerability — useful during ash teleports
See Build Planner for a Vex elemental preset.
Rewards
- Petrified Maw — Legendary shotgun, ~9 percent drop, fire-element with shock secondary
- Demon Heart — Guaranteed relic, +15 percent elemental damage
- Eridium — 250 guaranteed
- Crafting mats — Volcanic glass x12 for vendor crafting
Common mistakes
- Bringing fire into the magma phase. Watch HP — if it goes up, you are healing it.
- Standing on the open arena floor in phase 2 instead of the cooled vent rings.
- Trying to crit the head in phase 1. The head is decoy armor; the crack on the chest is the real crit spot.
- Skipping the forge altar. There is no second refill point.