Get the Geistesser's Skull

Journal
''This is it! I have all the components to enter the large looking-glass and confront the demon. I can use the looking-glass in the Highvale Outskirts monastery steeple to get to the room full of looking glasses, where I'll use the large looking-glass on the floor to enter his lair. Once I'm on his unhallowed ground and I defeat the geistesser, I'm to extract its skull and bring it back to Esmeralda so she can free Captain Burnes' soul. This is going to be a tough one - I feel like a fly jumping right into the spider's web!''
 * Note: After completing Tell Esmeralda of Ghostly Echo, speak to Esmeralda and manually type the words final step to receive this quest.