Cat nip,you found it in Via Infinito...
You'll find the Via Infinito in Bevelle (Chapter 5)..
Go inside Bevelle and turn right,you will found Pacce and his freinds.Follow Pacce into the Warp Place..
Make your way to Cloister 40 and then you have to fight Black Elemantal..cast Reflect,Shell and Protect to defeat that monster.
The fiend will always use Flare or Berserk and sometimes Ultima..
If the fiend uses Ultima it is..GAME OVER..
PS:You must cast the spells or not GAME OVER..
Team Locked In Silence
Thanks to RC for the super cool avy and sig!