My best party setup is:
1 Paladin who knows to rotate CD
1 Scholar who can solo heal the whole thing
6 of any DPS that can stay alive
That's it really. Sure final heaven is nice but not needed. Why not bring 6 monks? They have amazing dps on single target and can keep GL3 up mostly through the phases. And with that setup, you'll always have Dragon Kick up increasing damage to all of them and you can have Mantra back to back to back to back to back to back with downtime of only 30s lol.
Warrior only brings increased damage for him and Paladin btw.