How the devil are you supposed to get all 9 grimoires? I went through and got 5 (for the 5 that were in my party), and I tried leaving the dungeon and coming back with a new party, but no new doors would open. Beat Zeromus_EG and came back--no new doors would open, but it would still make me fight Zeromus_EG at the end. I even tried loading the saved game from before I entered in the first place and went in with a new party; it seems it'll only let me open doors if I go in with exactly the same party I beat Zeromus on.