In DH, while
Harry, Ron, and Hermione are infiltrating the Ministry,
Umbridge casts a Patronus to keep the Dememtors at bay.
But if she was capable of such a charm, surely she could have kept some centaurs at bay.
“Nooooo!” he heard Umbridge shriek.
“Noooooo . . . I am Senior Undersecretary . . . you cannot . . . unhand me, you animals . . . nooooo!”
He saw a flash of red light and knew that she had attempted to Stun one of them — then she screamed very loudly. Lifting his head a few inches, Harry saw that Umbridge had been seized from behind by Bane and lifted high into the air, wriggling and yelling with fright.
So how did she do it?