In Harry Potter 2 , Harry gives Mr. Malfoy Voldemort 's diary in order to free Dobby , Lucius takes it with him . How did Dumbledore -LRB- in the film , ca n't remember about the books -RRB- possess the diary again in HBP ?
Why does only Harry Potter have to kill Voldemort if Dumbledore had the strongest wand in the world ? Could n't he have killed him himself ?