Silver Sword (Enhanced): Into The Snow-Topped Fortress

Northeast of Kaer Gelen (accessed over the top of the mountain with a treacherous slide down to the fortress roof), and north along the coast (before cutting inland up the snow-topped mountains) from the Whale Graveyard are the remains of an ocean-facing fortress, now devoid of human life. Expect Harpies to attack as you reach the giant arch at the front of the structure.

Cross the fallen debris in the courtyard, check the right interior wall for a wolf sign, and prepare to repel a group of Necrophages once you enter the fortress. Once slain, head north to a hole down to a subterranean tunnel leading to two more Necrophages. Check the perimeter for chests, with the one you need to open at the opposite end to the tunnel entrance.