Well, there is nothing in here except one treasure:

• ITEM (T-01): Ethersol (x1)

At last, your long awaiting battle with the big boss. You will fight 3 battles consecutively. 

Paradigm (Lightinng/Fang/Hope):

• MED/SAB/SYN (default)
• RAV/COM/RAV
• COM/COM/RAV
• MED/SEN/MED
   
• BOSS (B-01): Barthandelus (x1)
  Strategy: Barthandelus? You fought this guy like 2 times already.
  • First throw 1 Librascope on him.
  • Start with MED/SAB/SYN until Slow, Deprotect, Deshell, and Imperil sticked on him.
  • Switch to RAV/COM/RAV and Lightning Spamming her "Army of One".
  • When the stagger is around 750% switch to COM/COM/RAV. He should go down in 2 staggers.

Paradigm (Lightinng/Fang/Hope):

• MED/SAB/SYN (default)
• RAV/COM/RAV
• COM/COM/RAV
• RAV/COM/MED
• MED/SEN/MED
   
• BOSS (B-02): Orphan (x1)
  Strategy: Pretty much the same as Barthandelus, except that this time you have to watch out for his attack "Merciless Judgement" which will bring your health below 100HP. When you see "Merciless Judgement" on his head, immediately switch to MED/SEN/MED for healing until green then repeat the process. he should be out in 2 staggers.

Paradigm (Lightinng/Fang/Hope):

• MED/SAB/SYN (default)
• RAV/COM/RAV
• COM/COM/RAV
• MED/SEN/MED
   
• BOSS (B-03): Orphan (x1)
  Strategy:
  • Same strategy, do I have to repeat myself here? put Deprotect, Deshell, and Imperil on him (He is immune to Slow by the way), then spam your "Army of One" until the stagger meter is around 800%, switch to COM/COM/RAV and finish him off for good.

Congratulations! You have finally completed Final Fantasy XIII story. The rest of guide are for completionists only.