Amygdala is a hidden boss in the game that many players will not come across naturally. To find the boss, follow these steps:
- Go to the Forbidden Woods and find the dog cages (there is only one place in the Woods that has dog cages, so it's fairly hard to miss). There is a house nearby with a lantern. Talk to the person in this house and he will give you an item called the "Tonsil Stone".
- Go to the room where you spawned immediately after defeating Rom, the Vacuous Spider (if you've forgotten how to get here, go to the lamp at the top of Yahar'gul, Unseen Village and then backtrack up the steps behind you). There is a giant monster hanging on the wall in this room who will try to grab you. Let it (if you don't have the Tonsil Stone yet, this will kill you).
- You will be teleported to a new section of the Nightmare Lecture Building (and hence will earn the "Nightmare Lecture Building" trophy if you haven't already). Follow the path to the end and you will end up in a new section of Mergo's Loft (the outside nightmare area). Make your way through this (fairly long and difficult) area.
- You will eventually cross a narrow bridge that leads into a large, open circular area. Once you reach the middle of this circular area, Amygdala will drop down, and you will fight it.
The strategy for Amygdala is to stay behind it at its tail. Most of its attacks take place in front of it or directly under it (so do not stand right under its hind legs or under its chest). Also, do not lock on, as that will just make it more difficult to target its tail. Just slash away at its tail and heal when necessary, and you should be OK as long as you avoid its frontal attacks.
You will earn the "Chalice of Ailing Loran" at the same time as this trophy. See the following video guide: