The Freedom Fighters achievement is split up into 3 'side quests' I guess you call them.
Each step has a different amount of 'runs' you need to complete to advance.
If you don't like reading I'll link a video below.
The first one is a dismembered shield maiden you have to defeat. Each time you kill her she gets a limb back. Once completed she will be patrolling the area and will help you with encounters. If you take the first right then hug left around the island there will be a zip line that takes you too a cave. She is in there, go forth and slay!
The second one is the easiest and only requires 2 runs. There is a dwarf in the first building who tells you his mates are being held captive in the forge and wants you to save them. In the first encounter one of the enemies will drop a key. For me it was the final enemy that dropped it.
Carry on through the encounters until you reach a giant stone building. Inside is another encounter, once these enemies are delt with there are 4 cages to unlock. Now you need to return to the dwarf at the start and he will thank you and boom side quest complete.
The final side quest has a few steps to it. Continue forward towards the tower in the distance. This map is a little confusing you have to go forward and a little left to then go right. Once you reach the bridge to the tower a fella will jump out and ask you to kill a druid. This druid is located in the tower in front of you. You will know you have got the right target as it will do that xray step animation. Once you kill him you will need to return to the beginning in a different run. The same guy will give you some beans to buy some rocks. The hidden merchant is located under the tower that the druid was in, so retrace your steps and get them stones. Again, returning to the beginning you will need to head left until you reach an encounter with a body lying under a tree. You will be able to place the stones around on the ground. Start the encounter and a white wolf will spawn. He can not be hurt by normal attacks, you need to kite it over the stones and it will take damage. Do this with each stone and it will die. Have a chin wag with old mate and the quest will complete and the achievement will unlock.
Chur 🛸