To do this, you have to get your plate, hold it flat and facing you (close to the wall but not touching it, because if you do it will glitch inside of the gate and you can't get through), and then use Whirlwind Sprint into the plate and through the gate.
You can find it by traveling South East of Winterhold and North Northeast of Windhelm. The Main entrance is locked and requires a key to open it. The door is unlocked during the quest Speaking With Silence.
Navigating Through Snow Veil Sanctum Once you make it to Snow Veil Sanctum, speak with Mercer, who will tell you that Karliah is inside. After speaking with him, walk to the locked door together and wait for him to unlock it.
Skyrim:Snow Veil Sanctum Nordic Ruin: Snow Veil Sanctum (view on map) Clearable Yes (see bugs) Dungeon Yes Respawn Time Never (storage is safe) Level Min: 613 more rows •
Track down the Dunmer behind the Guild's misfortunes. Quest Giver:Mercer Frey Next Quest: Hard Answers Reward: Gallus' Encoded Journal, Word for the Disarm shout ID: TG05 Suggested Level: 62 more rows •
If you managed to find the skill books, the model ship, and the dragon shout, and if you completed the quest in question, then there is no real reason for going back in there unless you wanted to sneak past Draugr that might have respawned.
Adds a Amethyst Dragon Claw to Snow Veil Sanctum, for the sake of collection. The Claw doesn't exist in Vanilla Skyrim because Mercer Frey opens the puzzle door using a certain item he has, but another character must have gotten in the room somehow....
Hard Answers is a Thieves' Guild quest received from Karliah after completing the quest Speaking with Silence.
Make your way to Snow Veil Sanctum and have a chat with Mercer who is waiting outside. Mercer will inform you that Karliah is hold up inside Snow Veil Sanctum, so lead the way to the door, which Mercer will unlock, and head inside.
Hard Answers is a Thieves' Guild quest received from Karliah after completing the quest Speaking with Silence.