This is strictly about mission 64. I breezed through every mission except this one. I probably spent 3 hours JUST to get 4 stars. I went back got the Master's Seal achievement. Once that was complete, I read a guide on each character and their abilities.
This fight boils down to two things. 1.Characters 2.Equipment.
1.Characters: This is really important. The whole game I played with Fang (L), Lightning and Hope. After reading math and abilities, etc, i decided that Lightning (L), Fang, Vanille was the best setup for this fight. Why?
You want to buff FAST when he [Impenetrable Aura]
*It is rather odd that only Vanille and Fang get the -ra variants of the buffs, despite neither of them having Synergist as a primary role. Vanille would actually make for a very good Synergist if only she had Haste, but seeing as how everyone else does, she makes for an excellent choice as a secondary Synergist. If you want to use a Paradigm with at least two of these, you'll be able to buff your party very rapidly.
*Obviously, Vanille and Fang are better because they have Dispel, while Lightning and Snow don't. Vanille also has poison. If you look at my Paradigm setup, you'll see that I have Vanille primarly as a debuffer. Right when he comes out of [Impenetrable Aura] switch to #2. Stay on #2 until Poison is cast then switch right to #3.
*You want Light as a healer during [Impenetrable Aura] so you can use Cura, Cura, Cura to TOP OFF YOUR HP. The AI is stupid and will not do this. Use this down time to be in a good position to burn him down.
There is a lot more detailed information about each character in the link below. Go to 3c Party Setup.http://www.gamefaqs.com/xbox360/950899-final-fantasy-xiii/fa...
2. Rav/Sab/Sab <- Start
Start in 2. Once poison is up, switch to 5... he'll go to [Impenetrable Aura] soon.
Once in [Impenetrable Aura], go to 1. Use Cura, Cura, Cura to TOP OFF YOU HP. Stay in this shift until he comes out of [Impenetrable Aura] and go right into 2. Once poison is on, go to 3. If you need to heal, go to 4. Once he is staggered, go to 5. Pretty easy!
It becomes tricky when he uses [Wicked Whirl]. As soon as you see it, go to 6. Once that is over, go to either 4 or 5 and repeat!
2.Equipment is VERY important. The less time you're healing means you can be debuffing/attacking.
Omega Weapon (Lionheart)
Kain's Lance (Taming Pole)
Nirvana (Belladonna Wand)