Assassin's Creed Valhalla features a complete set of Thor's armor. If you put the whole set on your character, you will make your stun more powerful. This guide page has a detailed description of how to get Thor's helmet. This is one of the most well-hidden chests in the game. Additionally, you must have a high level of experience to be able to get this item.
Daughters of Lerion
There are three Daughters of Lerion. They are the special enemies you have to defeat to get Goneril's Daggers. Thanks to them you will open the passage to the chest.
You have to defeat three women to get all the daggers:
The chest with the helmet is located in the eastern part of this region, in one of the caves.
Reaching the helmet
When you get to the cave where the helmet should be, you will see a large statue that stands in your way. To destroy it, you have to drive all three Goneril's Daggers into it.
When you place all three weapons into the statue, it will fall apart. You will see a passage – just run down the stairs and then keep moving straight until you reach the end of the cave.
There, you will see numerous treasures. The chest with the helmet is among them. Open it to get another armor part of the set.