Hermione finished removing his memories of the day. It had become a routine for her, repeated exposure to the obliviate charm caused his brain damage beyond repair. His mind was now perfect for the imperious curse, just a few days of waiting for the combustible liquid to stabilize. Muggle chemistry is so interesting, and it'll be undetectable by the Malfoy Manor wards. The Dark Lord would be angry enough at Avery, just any high-powered curse will do the trick.