The main battle of the Great Hall is against Macduff's Ghost. He is found in the room to the right of the stairwell. He is much easier to defeat if your party leader has the Cup of Drowning. Q: I already know my horoscope. Why should I explore Astrologia? A: In Astrologia you will learn that collecting the three items with Aldhelm's name on them will help you a lot in the last two rooms of Cawdor: the Bestiary and the Crypt. Similarly, collecting all three Alcuin items and all three Alfred items will help.