25 minutes on that last Boss should be plenty...if you are properly geared that boss goes down fairly fast. The part I see players have the most difficulty with is the flying AOE ice breaths that wipe people out because they do not dodge correctly. For Noob stick with someone who is dodging good and follow them. I found it helps to zoom the camera out...you can most of the time see the dragon in the air to judge how you should dodge although I would still stick to using the ground cues primarily. I have also found the wrong DPS in there can hang you up...I would try and take a BARD...it just makes life easier and they can also replenish MP if your healer needs to spam cures due to bad dodging.