Horizon Zero Dawn's Revenge of the Nora follows on straight away after The War-Chief's Trial.
While you can continue on with A Seeker At the Gates - which is where the previous mission stemmed from - you're likely not a high enough level to tackle it easily.
As such, we highly recommend getting the Nora questline done and dusted first, as it'll both level you and make narrative sense that way - plus, it's in the local area, rather than taking you to the gates and beyond.
If you're after help for other parts of the game, consult our complete Horizon Zero Dawn walkthrough and guide.
Revenge of the Nora - Red Echoes, Cultist Camps
Go to Red Echoes - It's time to track down more of these enemies. Red Echoes is a little while away, so we recommend picking up another mount, particularly for charging past some otherwise dangerous groups of patrolling machines.
Rest at the Campfire - When you're ready, rest at the Campfire nearby.
Clear the Camps (x3) - There are three to clear out, and they can be hard work the number of machines nearby. If you're being stealthy, take out the alarms which are marked by your Focus as big yellowish sacks, destroyed with one hit from your bow or spear. If you're going for maximum carnage, use the barrels of Blaze to blow up enemies in one hit, and prioritise the Watcher machines for overriding or quick kills first, as they're the highest threat!
Go to the Tallest Tower - With those three large camps wiped out, head to the meeting point nearby. Talk to Sona - Quickly catch up with her for a debrief.
Follow Varl - Instead of climbing the walls of your enemies' Metal Ring base, you have another idea for a stealthy approach. Head there with Varl.
Metal Ring and destroying the Blaze
Enter the Metal Ring - Keep following Varl as he says.
Search the Metal Ring for a View of the Blaze - There are a couple of stealth kills to take care of here. First involves either sniping or striking from above a guard on the right of the first two below you. Then, do the same with the right guard of the next pair from ground level.
Sneak to the Blaze - This objective isn't very clear. Really you're sneaking to a vantage point where you can shoot the blaze from. You definitely want to do this stealthily, tracking the Cultists' paths to know when you can get by. We suggest heading down the ledge to Cultist Dredger, sneaking just to the right of him into a long ditch along the side of the wooden structure, which is left of the big Corrupted Fire Bellowback. Use a stealth takedown on any straggling Cultists in the way, until you get to a point where you can see the large pile of Blaze barrels stacked up in a wooden structure.
Shoot the Blaze - Shoot them to blow it up!
Kill the Cultists and Machines - Now, the rest of the Nora can charge in. Wipe out the enemies there - prioritising the high damage machines first - and celebrate your victory.
For more Horizon guides, explainers and advice, take a look at our main Horizon Zero Dawn guide and walkthrough hub, or our advice on finding Horizon Zero Dawn's override Cauldrons for controlling any machine, and unlocking some super-strong armour with our Horizon Zero Dawn Power Cell locations guide, too.
With the Nora now finally avenged for the actions of these Cultists in their Proving assault, you're now free to continue your quest beyond the Nora lands out in the big wide world.