there not three ghouls there called hinkypunks(yes hinkypunks)and to kill them u have to use the lumus duo(light spell)that u just learned in that room.use it till it fades and then hit them with a flipendo(begining spell)or 2.that should do it!!hope i helped!
"it is not our abilitys that show what we truely are,it is our choices"~albus~