There are 6 Rebel Camp Locations in Horizon Forbidden West (HZFW). Investigating all Rebel Camps and then helping Erend defeat Asera unlocks the “Defeated Asera” trophy.
None of the Rebel Camps are missable. You can still find all of them after the story in free-roam.
After clearing the first 5 Rebel Camps you can track the 6th one under Quests > Rebel Camps > First Forge. This creates a waypoint to talk to Erend in the desert in the south of the map. Then you must help him clear out the last Rebel Camp for the “Defeated Asera” trophy.
Each Rebel Camp requires you to defeat the leader, scan some clues in the command center, and destroy some objects. When done correctly the camp icon on the map will turn from blue (incomplete) to green (completed). You can also keep track under Quests > Rebel Camps. Simply find the camps in the open world, they can be done in any order you want, except the last one which only unlocks after doing the first five.
Rebel Camp #1: Eastern Lie
When you arrive at the camp, the main gate will close down. Circle around the hill to the right side of the gate to enter the camp. Then find the camp leader in the north-west side of the camp, climb up the rocks there. Where you defeat the leader you can scan for a clue (gets marked in purple), interact with it. Then two more clues spawn in the same place, interact with those too. Lastly you must destroy the blaze canisters, which are found in the north-east corner of the camp, behind the campfire fast travel point. You can shoot the blaze canisters from afar.
Rebel Camp #2: The Hive
In this camp you have to destroy 4 piles of weapon caches. You can scan for them by holding and they will be marked in yellow, makes them easier to locate. The 1st pile is in a building in the center of the camp, from the camp’s main entrance it’s straight ahead and slightly to the right (bottom floor of building). The 2nd is also in a building in the center of the camp, from the camp’s main entrance it’s to the left (bottom floor of building). The 3rd is next to the campfire fast travel point, from the camp’s main entrance it’s to the left, next to a weapons rack. The 4th and last one requires shooting the red lock of the yellow ladder next to the campfire fast travel point, climb up, then go straight and and the next turn look right, under another weapons rack.
Also kill the camp leader, who is up the hill near the 4th weapon cache (south-east corner of the camp). Lastly, scan all clues in the command center where the leader was, as usual scan for them with to see them highlighted in purple.
Rebel Camp #3: Devil’s Grasp
First go to the west of the camp and destroy the “Override Equipment”, which looks like a big power transformer. It gets highlighted when scanning with . Then head to the southernmost point of the camp, there you can drop down into a pit with 3 enemies, one of them is the camp leader. Kill them all, then loot the leader and search the clues at the same location.
Rebel Camp #4: Fenrise
The leader is in the south of the camp, guarded by many other heavy enemies. Take him out, then scan the clues in the command center where he spawned. Afterward, head to the north side of the camp to clear out the Rebels. Some allies will spawn to help you win the fight. Then talk to the Squad Leader to finish this camp.
Rebel Camp #5: Breached Rock
After entering the camp through the main entrance, kill the big armored enemy with a blue energy shield. Search his body for a Bunker Key. Drop down into the pit in the middle of the camp and keep heading down the path into the ruins, behind some wooden barricades. There you can use the looted Bunker Key on a console to open up the bunker. Head inside and kill the leader, then scan all the clues and interact with them. Lastly, activate the console to blow up the bunker, it will automatically teleport you back outside. If you also completed all other Rebel Camps you should get a new Rebel Camp added to your Quest Log called “First Forge”, be sure to track it for a quest waypoint in the desert area in the south of the map.
Rebel Camp #6: First Forge
After clearing the first 5 camps, press Touchpad > Quests > Rebel Camps > First Forge > Track this Quest. Head to the quest start at the settlement “Hidden Ember” in the desert area in the south of the map. This is the final part of the Rebel Camps questline. There you must talk to Erend, he will mark the 6th Bandit Camp “First Forge” in the north-west of the map (see 3rd and 4th image above). Head there, interact with the campfire, then you and Erend will enter the Camp. Defeat all enemies, interact with the door, then follow Asera and defeat her. Don’t forget to loot her legendary hunter bow from her body afterward (“The Sun Scourge”). Talk to Erend and after the cutscene you will earn the “Defeated Asera” trophy.
That’s all 6 of the Rebel Camps in Horizon 2: Forbidden West (HZFW).
For anything else needed to 100% completion, check out the full Horizon Forbidden West Wiki & Strategy Guide.