Prisoner Azkaban

How do you get past the ghost during Neville and Ghoul in Harry Potter and the Prisoner of Azkaban?

I’ve got the light spell and i’ve killed the ghost so many times (their already dead thoe…) but more keep on reappearing! I need help on beating them!

i think i no whats wrong

u need keep the light spell on them until they are almost completly opaque or visible then quickly cast flipendo, if u did it right they shud just dissapear.
hint: 3 more appear after the first 3 but thats all
(ps2 btw)

Harry Potter and the Prisoner of Azkaban Theatrical Trailer