Final Fantasy six dragons den

Umm... in the new final Fantasy six, i beat the eight dragons and the game, but a friend of mine says there is this Level called the dragon's den...
1. Where is iT? i really can't seem to find it.
2. is my party good enough?
I have:
Celes: Lvl. 69
Hp: 6851
mp 795
Str. 72
Locke: Lvl. 45
hp 3123
mp: 556
Str. 41
edgar: Lvl. 64
Hp. 5815
mp: 752
Str. 53
Mog:level 65
hp. 7398
mp. 753
str. 753

Everyone knows ultima, all the -aga speelss, flare, Curaga, Arise, metor, and Imp, along with Celestriads. I gave the soul of thamasa to Celes.

3. Is there anything I need to know?