I feel that I should point out that when the black mist lifts and Hermione recognizes the face of her assailant we have no reason to believe that the face she recognizes is not itself an illusion.
Since we already know that she has been obsessing about Draco, I suspect that it may even have been his face (though with the information we readers have it is obvious that H&C is not actually he), though I don’t put a great weight on that suspicion.
I feel that I should point out that when the black mist lifts and Hermione recognizes the face of her assailant we have no reason to believe that the face she recognizes is not itself an illusion.
Since we already know that she has been obsessing about Draco, I suspect that it may even have been his face (though with the information we readers have it is obvious that H&C is not actually he), though I don’t put a great weight on that suspicion.