What is Hamlet referring to in the passage Up sword and know thou a more horrid hent when he drunk asleep or his rage incestuous pleasure of bed?

Hamlet is referring to the murder of his father, King Hamlet, by his uncle, Claudius, who then married his mother, Gertrude. Hamlet is disgusted by the incestuous relationship between Claudius and Gertrude and vows to avenge his father's death.