The final step in obtaining the Chalice containing Queen Yarnham, needed to obtain the platinum trophy in Bloodborne. I highly recommend you get yourself to the hardcap of 50 points in at least your Health stat before doing this fight. Amygdala also does arcane based attacks in phase 2 and 3 so I suggest you gear yourself with that in mind. I also found that having a couple of communion runes equipped was essential as those extra Blood Vials can save your life. Good luck to you hunters. May the next time we meet be over the lifeless body of our dear Queen Yarnham.
Bloodborne: Defiled Chalice Boss Amygdala Strategy