By the time the students left for Hogwarts, Harry had at least managed to keep the nightmares away (Sirius noticed a lack of bags under the teen’s eyes, at least, so he was getting more sleep than he had been) and all four Gryffindors had at least enough spell knowledge to hold their own against lower level Death Eaters and trainee Aurors. Ron knew some, but he wasn’t very willing to do the extra studying the others did.