Danni's departure from the show is somewhat controversial. She is shown getting hit with a staff, then falling to the ground. Some believe her to have died, while others think she's still alive somewhere. It's possible that since the blow she took wasn't very powerful, she's still alive somewhere. Since the Chosen were defeated in Series 3, she may have been freed and just decided to go her own way since she may have heard about Amber being alive again.
Final time the version of "Abe Messiah" sung by the Series 2 cast is used as the ending song.