In God of War Ragnarok, The Lost Treasury is a sub-region of the Lake of Nine in the realm of Midgard that you need to access in order to complete the Sigrun’s Curse side quest Favor. To get inside The Lost Treasury, you need the two halves of the Fjortlund Key, but even before you can reach the gate that the key opens, you need to complete a difficult puzzle whereby the giant shield from the statue of Tyr that once stood in Midgard is blocking your way into The Lost Treasury.
Related: All Odin Raven locations in Midgard in God of War Ragnarok
How to get through the gate behind the giant shield at The Lost Treasury
First, grab the shield using your Blades of Chaos, and pull it to the right.
Now climb the shield and get onto the ledge to the right. Throw a weapon at the pot to make the pillar collapse sideways. Cross the rooftop to the south, then drop back down to the ground.
Pull the shield back over to the left, then climb up its left side.
Head back over to the north side of the roof, and pull the fallen pillar to the left as far as it’ll go.
Drop back down to the ground and pull the shield to the right. The pillar should stop it so that the gap lines up with the gate.
Now, grab the wheel in front of the shield, and pull it all the way down so that the gate opens.
Without letting go of the wheel, throw your Leviathan axe at one of the gears on either side of the shield. Shoot a Sigil Arrow at the frozen gear, then recall your axe and throw it at the other gear. Let go of the wheel, and the gate should stay open. So get inside before the gears unfreeze.
