Locating the Hidden Chamber
Head to Sindri’s Shop at the Foothills and climb the wall ahead to reach a path with Scorn Poles. Take the right path first and then continue to follow the path to the right to reach a cave, the Hidden Chamber is situated at the back here.
Exploring the Hidden Chamber
Take the elevator down and activate the Mystic Gateway at the bottom before climbing the stairs to find a coffin. Turn around and look above the stairs you just climbed to find a Raven then go back downstairs to open a Hacksilver chest before leaping the gap. Take the left stairs down to find one final Hacksilver chest before entering to the central chamber to find the Valkyrie, Geirdriful.