God of War Ragnarök

Towards the end of chapter 10 of the main story (Forging Destiny) you should encounter Durwin stood next to a Mystic Gateway. Speak to Durwin and he'll speak of a lost Dwarven hammer which will start the favour "Spirit of Rebellion".

Collecting the hammer requires you to go back to Svartalfheim. Following the quest marker will take you to the shore of an island. Ignore the nornir chest. Defeat the enemies then climb the chain to the left of the chest.

There should be a rock to spear and blow up to proceed. Keep making your way up the dock finally reaching a blue seal on your left. Interact with it to make a rune appear. Interact with the rune to move a boulder and reveal a chest. The hammer is in the chest.

Once you have the hammer, return to Durwin (follow the quest marker to a Dwarven tavern) to complete the favour and get this trophy.