Why did the Death Eaters want Slughorn?

He wanted Slughorn murdered. Slughorn was to Voldemorts knowledge the only man who knew about Tom Riddles horcrux fascination. He might have also known Riddle became Voldemort, judging by his fear of Death Eaters which would seem to be unwarranted for someone of no serious note, nor of conviction against Voldemort.

Who was Horace Slughorn hiding from?

Death Eaters
Rowling describes Slughorn as “remarkably unabashed for a man who had just been discovered pretending to be an armchair” (p. 64). Slughorn is not at all concerned that he was caught or even found. Now we are led to believe that he is hiding from Death Eaters.

How did Slughorn’s information on Horcruxes actually help Voldemort?

How did Slughorn’s information on horcruxes actually help Voldemort? It’s no secret that Horace Slughorn gave Voldemort information on making horcruxes, and a major thrust in the sixth book is Harry and Dumbledore trying to find out what Slughorn told him.

What did Slughorn say to Tom Riddle that helped him?

What helped Tom Riddle was not so much what Slughorn said, but the two things he did not say: Something like “no way, splitting a soul a second time leaves too little intact, it would destroy all soul pieces”, possibly backed up by the story of someone mad enough to try and fail, would probably have stopped Tom from creating more than one Horcrux.

How did Riddle know how to make a Horcrux?

“Dumbledore was sure Riddle already knew how to make a Horcrux by the time he asked Slughorn about them. I think you’re right, Hermione, that could easily have been where he got the information.” Mithrandir’s answer already provides one relevant quote, but I’d say it lacks interpretation.

What does Dumbledore tell Harry about Slughorn’s memory?

While Dumbledore brings Harry to his office and reveals to him one of Slughorn’s memories from his younger Hogwarts days when he taught Tom Riddle, Dumbledore tells Harry that this memory has been tampered with.