I commented elsewhere that this is a major difficulty with trying to save her. Invisible Hermione would have to scream in the middle of combat to fake out the patronus, which is obviously an incredibly dangerous thing to do.
Hmmm… it’s also possible in that scenario that Hermione was hot-swapped out of the combat. Real!Hermione responded with a terrified scream to the Patronus, and while Present!Harry was racing to her on a broom, Time-Turned!Harry did some kind of obscuring spell (fog, blast of light, something like that), tossed an invisibility cloak (not Harry’s) over Real!Hermione, and then fed Simulacrum!Hermione to the troll just in time for Present!Harry to show up.
I commented elsewhere that this is a major difficulty with trying to save her. Invisible Hermione would have to scream in the middle of combat to fake out the patronus, which is obviously an incredibly dangerous thing to do.
Hmmm… it’s also possible in that scenario that Hermione was hot-swapped out of the combat. Real!Hermione responded with a terrified scream to the Patronus, and while Present!Harry was racing to her on a broom, Time-Turned!Harry did some kind of obscuring spell (fog, blast of light, something like that), tossed an invisibility cloak (not Harry’s) over Real!Hermione, and then fed Simulacrum!Hermione to the troll just in time for Present!Harry to show up.