One of the biggest advantages you have as Aloy in Horizon Zero Dawn against the many machines is the ability to Override their programming. You do this by using a piece of advanced technology recovered from the first Corruptor. Once you have the Override tool attached to your spear, you just have to sneak close enough to an unsuspecting machine to hack into them with a quick animation. This then converts them into your ally for a short period during combat or allows you to use them as a mount to move about Horizon’s map.
Because the Override ability can be used to turn some of the most dangerous machines into allies and provide you with a massive advantage in combat, you won’t immediately have the knowledge to hack into their systems. That’s where the Cauldrons come into play, which are essentially the dungeons of Horizon Zero Dawn.
Each Cauldron you come across while exploring Horizon Zero Dawn will be defended by a few packs of machines or bandits and require you to navigate through a series of platforming puzzles to reach the central core. Extremely powerful machines like Thunderjaws and Ravagers tend to guard these cores too, so always come prepared for a fight with plenty of ammunition and healing supplies. Once you’ve dealt with the machines and accessed the core, you’ll then gain the ability to override a new set of machines while playing the game, giving you a leg up in countless combat situations.
In total, there are five override tiers to unlock in Horizon Zero Dawn: PSI, SIGMA, RHO, XI, and ZETA. While you’ll gain access to PSI through the main story quest “Womb of the Mountain,” the others must be completed on your own. So, if you’re looking to unlock as many overrides as quickly as possible, here’s exactly where to find them on the map and what you should expect to find inside each Cauldron.
Located relatively close to Mother’s Heart and built into the side of a gigantic mountain, Cauldron SIGMA is a pretty easy dungeon to work your way through during the early hours of Horizon Zero Dawn. During your journey to the core, you’ll encounter a few simple platforming puzzles and a small army of Watchers that you can deal easily pick off with a heavy-hitting bow from a distance. Once you reach the core, you’ll be up against a Fire Bellowback and another handful of Watchers — just make sure to set down a few traps and use a weapon with freezing capabilities, and you’ll be able to clear the core room in no time. Then, just override the core and you’ll be able to hack into Sawtooths, Scrappers, Grazers, and Lancehorns.
You’ll find Cauldron RHO once you’ve passed through Daytower by clearing out all the corrupted machines scattered about Aloy’s homeland. After you’re through the small border outpost, head south along the mountainside until you find a small carved out section with an inactive ancient bridge. Deal with the Watchers protecting the entrance, and then head down into the crevasse to access the Cauldron itself. Inside, you’ll find a dozen or so Watchers scattered about, backed up by heavier machines like Longlegs and Ravagers, but if you keep your distance and stick to the shadows you’ll easily be able to avoid any dangerous encounters until you reach the core. Here, you’ll face a Snapmaw along with a Ravager, as well as a few Watchers. Once again, use traps and be sure to focus one down at a time with some Tearblast arrows, and the core will be yours for the taking. RHO teaches you how to hack into Tramplers, Shell-Walkers, Snapmaws, Longlegs, and Ravagers.
Down at the southern end of Horizon Zero Dawn’s map, you’ll find Cauldron XI tucked away in a forest. Instead of being protected by a set of Watchers, XI is home to a set of bandits who have established a series of encampments you’ll have to work through while also dealing with small packs of Watchers. Make sure to use the bandits Blaze canisters against them while fighting, or take a stealthier approach by sneaking through their ranks and eliminating whoever stands in your way. Once you’re at the core, you won’t fight a set boss machine but instead, waves of bandits who will come to attack with some support from weaker machines. Feel free to hack into a few of them with your override ability to cause some chaos or just tear through whoever stands in your way without creating confusion within their ranks. Either way, you’ll gain the ability to override Glinthawks, Freeze Bellowbacks, Fire Bellowbacks, Behemoths, and Stalkers.
The final and most difficult Cauldron is Cauldron ZETA. It can be found at the northwest corner of the map behind an entrance that is kind of hidden. Look around for a ridge where a Watcher is attacking you from a distance, and use the nearby pillar to climb up. Then, deal with the Watcher and slide down to the entrance. Once you’re inside, you don’t have much ground to cover before you make it to the core, but you’ll soon find out that ZETA is all about a difficult battle, one which puts you up against a Thunderjaw and a few other machines supporting it. This fight is all about preparation and strategy, meaning that you’ll want to use a good Tripcaster to continuously lock the beast down and then punish it by removing its protection with Tearblast arrows. Ideally, you’ll want to go for the Thunderjaw’s launcher first, removing it with arrows and claiming it as your own. Then, use it to tear through the armor and health of the Thunderjaw while avoiding attacks to claim the last set of override codes as your own. These will allow you to control the larger machines of the world: the Stormbirds, Thunderjaws, and Rockbreakers.