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Cauldron RHO is an activity in Horizon Zero Dawn. It is a HEPHAESTUS facility that manufactures machines for use in terraforming.


The entrance of RHO is a large triangular door, guarded by Watchers and Scrappers. Inside, the Cauldron is a twisted mass of metal walls, machinery, and wires, similar to Cauldron SIGMA. However, RHO has a number of unique machinery operating in the area, such as giant wheel-like devices. Also, RHO will open into natural caverns. The most notable part of RHO is a giant mechanical "heart," which pumps Blaze to unknown locations. The entire Cauldron appears to be the region's primary collection and distribution hub for Blaze.

The core area contains a Snapmaw being assembled. Once a pillar is overridden, the field drops, and the Snapmaw attacks, accompanied by a Ravager. Once these two machines are defeated, Aloy is able to override the core, obtaining the RHO overrides.

RHO Overrides


  • Find an Entrance
  • Investigate the Tunnel
  • Explore Cauldron RHO
  • Find a way through the Blaze Processing Chamber
  • Find the Cauldron Core
  • Override the Core


The following datapoints are obtained automatically during this quest and cannot be missed.

Text Datapoints - Machine


Horizon Zero Dawn Quests
Main Quest A Gift from the Past - Lessons of the Wild - The Point of the Spear - Mother's Heart - The Proving - The Womb of the Mountain - A Seeker at the Gates - The War-Chief's Trail - Revenge of the Nora - The City of the Sun - The Field of the Fallen - Into the Borderlands - The Sun Shall Fall - Maker's End - The Grave-Hoard - To Curse the Darkness - Deep Secrets of the Earth - The Terror of the Sun - The Heart of the Nora - The Mountain That Fell - The Looming Shadow - The Face of Extinction
Side Quests A Daughter's Vengeance - A Moment's Peace - Acquired Taste - Ancient Armory - Blood on Stone - Cause for Concern - Farewell - Death from the Skies - Fatal Inheritance - Heap of Trouble - Honor The Fallen - Hunters' Blind - In Her Mother's Footsteps - Insult to Injury - Queen's Gambit - Redmaw - Robbing the Rich - Sun and Shadow - Sunstone Rock - The Forgotten - Traitor's Bounty - Underequipped - Weapons of the Lodge
Errands A Curious Proposal - Collateral - Deadliest Game - Demand and Supply - Hammer and Steel - Healer's Oath - Hunting for the Lodge - In Foreign Lands - Luck of the Hunt - Odd Grata - Sanctuary - Shortage of Supplies - Sun's Judgment - To Old Acquaintance
Activities Bandit Camps Blackwing Snag - Devil's Thirst - Gatelands - Hollow Fort - Shattered Kiln - Stone YieldFW - Two-Teeth
Cauldrons Cauldron RHO - Cauldron SIGMA - Cauldron XI - Cauldron ZETA
Corrupted Zones Corrupted Zones
Hunting Grounds Greatrun - Nora - SnowchantsFW - Spurflints - Sun Furrows - Valleymeet
Tallnecks Devil's Thirst - Copper Deeps - FrostfiguresFW - Rustwash - Spearshafts - Sun-Steps
Horizon Zero Dawn: The Frozen Wilds Quests
Side Quests Firebreak - For the Werak - Frontier Justice - Into the Frozen Wilds - The Forge of Winter - The Hunters Three - The Shaman's Path - The Survivor - Waterlogged
Errands A Secret Shared - Ikrie's Challenge - Geared Up: Forgefire - Geared Up: Icerail - Geared Up: Stormslinger - Out of the Forge - The Claws Beneath