The second floor of the lecture building is another required area when pursuing the story in the game. To access this location, you must first defeat The One Reborn and interact with a mummy at the Advent Plaza which will transport you to this location.
Once you’ve arrived, exit the room you find yourself in and go straight into a circular lecture room where you may pick up some Sedatives from a corpse. Now, go back up and walk straight ahead to open the door at the end of the room. Watch out for some Graduate Beasts that may jump at you from the ceiling too. After this open the door to another room and read a couple of notes.
As you continue on, you may come across a Giante Gravekeeper which will give you Twin Blood Stone Shard. After the Giant Gravekeeper, you may find another room which lies on top of the lecture room you entered before. While here, you may also find a chest that contains Communion located in another small room.
Go back to the place where the Giant Gravekeeper was patrolling earlier and pick up the Blood Stone Chunk from one of the corpses in the hallway. After this, descend upon the ladder near the Giant Gravekeeper and this is where you will find Patches, a human and spider hybrid, who begs for his life.
Patches is not aggressive at all so you may choose to spare his life. After doing so, Patches will grant you the gesture “Beg For Life”. If you continue to talk to Patches, he will give you Anti-Clockwise Metamorphosis runes.
After meeting Patches you may unlock the door that was previously locked during your first visit to the lecture building or you may proceed with the story by going up to the second floor and passing through the black mist or vortex on the door that will lead you to the Nightmare of Mensis.