Mercer explains that they belonged to Karliah, your quarry. The first thing he saw outside the ruin was a dead horse, its throat slit with a knife. Where do you get the key to go inside? share. You will be send to Snow Veil Sanctum and you need to fight your way towards the puzzle door of this Sanctum. Mercer Frey will meet you outside the sanctum, and he'll begin following you. Um, didn't find a 'key' to get past that puzzle door. 'You're late,' Mercer's voice called out, … As expected of any Nordic Ruins, the Snow Veil Sanctum is full of draugrs.
It is located in the ruins of Snow Veil Sanctum an ainceint Nordic tomb filled with Draugr.
