The iron door on the left is the one we couldn't open from the outside earlier. After opening it, you'll be at the entrance to the first floor of the Killing Intent Tower.
Now open the door and head out to the teleport point above. Activate the teleport and travel to the "Post Station".
Teleport to the Post Station. First, talk to Yu'er nearby and give her the three types of medicinal herbs you've collected. After completing the "Apprentice Physician" quest, you'll receive the survival accessory "Aromatic Medicine Box".
