New artifacts just made it to Genshin Impact with Patch 2.6 of the game adding two new sets that can be obtained from the new domain. Here's to unlock the Lost Valley Dungeon.
How to solve the riddle of the Lost Valley Domain in Genshin Impact?
Once there, you will have to locate the huge Geo pillars , one of them emits energy. This is where the puzzle starts. For the ending point, walk along the pillars heading west. You will see a pressure plate and torches. Pay no attention to that, but rather look behind. You will find a unique stone there. You will therefore have understood that if there is a stone and a pillar, it means that we are going to talk about Geo resonance.
This is indeed the objective of this puzzle, to break the rock using resonance. To get there, use the Geo Traveler or Zhongli if you have it to place a construct next to the pressure plate. Then, simply return to the pillar generating the energy and place a second construction to trigger the resonance. If all goes well and you have placed your buildings correctly, a cutscene will trigger.
Now all you have to do is enter the cave to find your much sought-after dungeon. You are now ready to collect the new sets while having recovered a teleportation point, a few primo-gems and a success. Be careful though, because the Gouffre still holds many mysteries.