Taken from the official website

This is amazing...this trailer is amazing, the storyline is getting pushed ahead little by little, the storyline of this game is starting to become something very very entertaining


So they took on Ozma in the otherverse and after defeating Ozma, the injured Priest started to transform into a Demon, basically Ozma cursed him or something like that...too amazing

Oh, and another trailer that commemorates all the past important updates and foreign versions~
I guess the most important thing is the "reach 300 million players(accounts) worldwide" in May, 2011.