There are six Cauldrons to complete in Horizon Forbidden West, but only Cauldron TAU and GEMINI are tied to the main story. The other four Cauldrons are optional, but they will unlock some valuable machine overrides, including the Clawstrider mount. Cauldron TAU, also referred to as Repair Bay TAU, has a recommended level of 15 and will need to be completed during "The Dying Lands" mission. This is the sixth story mission to complete in Horizon Forbidden West.
Cauldrons are essentially dungeons in Horizon Forbidden West where Aloy must fight various machines, complete platforming challenges, and defeat a boss before overriding the core. Each Cauldron has full and partial machine overrides to unlock as well as varying amounts of experience and skill points to earn. Since Cauldron TAU is tied to the main story, it should be the first one players complete. It's also the Cauldron with the lowest recommended level, with the next one being Horizon Forbidden West's Cauldron MU at 18.
Cauldron TAU is located west of Plainsong and will be marked on the map as soon as "The Dying Lands" is started in Horizon Forbidden West. On a mission to restore GAIA, Aloy, joined by Zo and Varl, must enter Cauldron TAU in search of Minerva. Like most of the other Cauldrons in Horizon Forbidden West, Repair Bay TAU can't be accessed through the front entrance. Instead, Aloy will need to find another way through by exploring the Sacred Cave and locating a Cauldron door to override.
In order to complete Cauldron TAU, players will need to locate and override the core. Near the entrance, there will be some Leaplashers to fight and another Cauldron door to override. Horizon Forbidden West's Aloy will need to defeat the machines and override the door to proceed down the tunnel and into an open area. The objective will then change to finding a way up, which involves using the large spinning mechanisms in this area.
In order to get the moving machines lined up, Aloy will need to stand on the glowing yellow triangle. As the machines spin, the circle on the moving piece will glow yellow when it's in the right position. For all three machines, Aloy will need to shoot the circle when its glowing which will lock the machine in place. After all three are lined up, Aloy can climb up to reach the ledge above. On the next platform, there's another triangle-shaped button to weigh down, but this time Horizon Forbidden West's Aloy will need to find something to place on it.
Next to the button, there's a ledge to climb up with a breakable wall. Behind the wall, there's a crate and a room with a barrier. The crate needs to be pushed through the barrier, then Aloy can jump back down and position it onto the triangle button. The next set of moving machines can then be lined up using the same method as the previous set of mechanisms. Aloy in Horizon Forbidden West can shoot the glowing circles to lock each machine into place, then she can climb up and go across to the other side of the room. There's one more triangle button with some moving machines to line up. Once they're locked in, players can climb up and move on to the next area.
The next room has a retractable ledge that Aloy can use to get across the gap. After getting across the gap, players can continue down the path until reaching a ledge adjacent to a mechanical arm. Aloy can climb up the arm to reach the ledge where there's a Network Uplink. Overriding the Network Uplink will reveal a room with flying machines. Aloy can glide using the Shieldwing in Horizon Forbidden West from the nearby ledge to the platform with vents to climb. The vent doesn't stay open, so players need to quickly climb up and cross the platform to reach the flying machines. Aloy can grab hold of one of the machines, then glide down to the platform where another Network Uplink is located. Overriding the last Network Uplink will lead to Cauldron TAU's core room where a Grimhorn boss will need to be defeated. In the middle of the room, there's an override console that will initiate the boss fight.
Grimhorns in Horizon Forbidden West are weak against Acid and Purgewater damage, so equipping Aloy with the right weapons can make the fight much easier. The Grimhorn will use its horns to shoot fire, but they can be detached or destroyed if Aloy hits them enough. Aloy can also shoot the Blaze Sac on the Grimhorn to cause an explosion dealing a large amount of damage to the machine. Throughout the fight, the Grimhorn will also use charge and stomp attacks that need to be avoided, so players should constantly be moving.
At some point during the battle, other machines will enter the arena, but Aloy's allies should keep them busy. However, once the Grimhorn is down, players will need to take out any remaining machines before moving on. After defeating all the machines in the area, a cutscene will play showing Aloy overriding Cauldron TAU's core. Interacting the core again after the cutscene will unlock the machine overrides, then Horizon Forbidden West's Cauldron TAU is complete. Players can then exit Cauldron TAU and continue to the next main story quest, "The Eye of the Earth".
There are only three machine overrides to unlock for completing Cauldron TAU, but one of them is the Bristleback full override. Bristlebacks are fast and powerful machines that can be used as mounts after completing Cauldron TAU. The other two machine overrides are corrupted, so Aloy will need to finish crafting them at The Base. Along with machine overrides, players will earn experience, two skill points, and the Utaru Whisperer Face Paint in Horizon Forbidden West. Completing the Cauldron TAU is required to complete the main story, and it has a few worthwhile rewards for clearing it.
Horizon Forbidden West is available for PlayStation 4 and PlayStation 5.
