What is this chapter mainly about?
How does someone create a Horcrux?
What seemingly random number of Horcruxes does Tom Riddle ask Slughorn about?
Why did the diary alarm Dumbledore?
Why does Dumbledore think Voldemort actually returned to Hogwarts after leaving for years?
What is the only known relic of Gryffindor?
What is the "power the Dark Lord knows not" that Harry possesses, as referred to in the prophecy?