What is the deed of dreadful note?

The "deed of dreadful note" refers to the murder of King Duncan in Shakespeare's play "Macbeth." This act is pivotal as it marks Macbeth's descent into tyranny and moral decay. The phrase underscores the gravity and Horror of the crime, which sets off a chain of events leading to Macbeth's downfall. It encapsulates themes of ambition, guilt, and the consequences of unchecked power.