He accidentially cursed Katie Bell via the opal necklace, when he tried to get her to deliver it to Dumbledore. Also, in the book he placed Madam Rosmerta under the Imperius Curse in order to have a contact in Hogsmeade.
There is no specific incantation, it depends on what you are vowing about. In Half Blood Prince Snape vows to keep Draco safe, to watch over him and to perform the task he is set should Draco fail.
In the half blood prince after he cursed Katie Bell
NO. Just sad.
Draco Malfoy, hoping that the necklace would get to Dumbledore.
No. Ron and Lavender have a romance, and Harry and Ginny have a romance. Hermione likes Ron. Draco Malfoy does not have a romance with Hermione Granger.
There is no specific incantation, it depends on what you are vowing about. In Half Blood Prince Snape vows to keep Draco safe, to watch over him and to perform the task he is set should Draco fail.
No, Severus Snape is.
half-blood prince
No he didn't.
Snape
In the half blood prince after he cursed Katie Bell
Harry Potter
Tom Felton
NO. Just sad.
Snape, Draco, and Billatrix
He goes to the room of requirement.
Madam Rosmerta