From the Grand Cathedral take a left and make your way through the area where you fought the two Hunters and two Executioners to access the church that leads toward Yahar’gul, Unseen Village. As you walk toward the doorway the Lesser Amygdala will grab you, but instead of avoided it you’ll want to get sucked in to reach the Lecture Building 1F.
Light the lamp and cross the hall to speak with Patches the Spider through the doorway, though he has nothing to say at the moment. Stay on this side of the hall and enter the first doorway, followed by another, to enter the first lecture hall where a Scholar will fall from above.
Grab the Lecture Theatre Key and Student Set from the room and then exit out the other side to enter the circular room next door. Here you’ll find a Madman’s Knowledge x2 , but beware of the Scholar that falls from above. You can now cross the hall, ignoring the glowing door, and enter the first room for a chest with Red Jelly x2 .
Follow this side of the hall to use the Lecture Theatre Key to enter a room is filled with Scholars, so back up and let them clump together before you dash in for a few hits and then retreat. Once all the enemies are dead, exit through the opposite door and pick up the Augur of Ebrietas and then return to the glowing door to enter the Nightmare Frontier.