This sidequest follows directly after The War Chief's Trail and acts as the conclusion to this little part of the story. Head for Red Echoes, then when you get there, activate the camp fire to start a cutscene. Once it’s over, first order of business is to take out three Cultist camps. It doesn’t matter which order you do them in, but each one will have an array of human enemies, with a sprinkling of corrupted machines, and an alarm they’ll set off if given half the chance. The best tactic is to get to the edge of the camp, find where the alarm is and disable it quietly, then start the fight openly as the Nora war party will join in to aid you once fighting starts.
When all three camps are down, it’s time to move in for the main one. Follow your waypoint through the ruins until you find Sona. Be aware that there will be patches of corrupted machines that you’ll either need to stealth around, or kill, on your way there. Once there, talk to Sona and you’ll get the next part of the mission, blowing up the Blaze store. Follow Varl to the wall, then talk to him to scale it and enter the Metal Ring. Now it’s a stealth game. Stick to the rafters until you can’t go any further and Varl tells you to take the one on the right. You can stick to that, although in reality, as soon as you attack one, he’ll jump into action as well, so just pick a bad guy and get to killing.
Once they’re dead, follow Varl until you reach the next two guards and take them out too, then head forward until you reach a climbable ledge. Get up on top of that and a cutscene will start. When you’re back in control, you need to sneak your way through the camp to get a shot on the Blaze containers. Helpfully there’s a path down to the Blaze that, if you’re careful, you can sneak down until you can see the Blaze. Take the shot with a fire arrow, and watch the explosion. Now all hell will break loose though. There are a lot of bad guys, corrupted Watchers and a corrupted Bellowback for good measure. The Bellowback is easily the most dangerous thing, so look to taking that out first.
Hit the weakpoints, and definitely use your tripcaster Blast wires to deal significant damage to it. Once it’s down, mop up everything that’s left, and keep yourself aware for enemies flanking you and hitting you from behind as you’re aiming at another one as this is going to be the most likely way you’ll die. When every enemy is down the quest is complete.