Episode 22: Bloodborne Platinum Trophy Guide - Lecture Building. To reach this location, let the Lesser Amygdala in the church to the right of the Grand Cathedral kill you while having the Tonsil Stone in your inventory. You'll see a cutscene then you'll be deposited next to the lamp on the first floor of the Lecture Building. Alternatively you can get to the Lecture Room 2nd floor by beating the One Reborn, and just past him through Advent Plaza, there is a mummy that you can inspect that teleports you to the 2nd floor lamp of the Lecture Building. Important items & events:

4:40 - Communion rune
6:05 - Patches the Spider NPC (Anti-Clockwise Metamorphosis rune)
8:30 - Lecture Theatre key
9:40 - Red Jelly location
11:30 - Augur of Ebrietas