Minor Spoilers for chapter 8:
Yuliana + Ominas + Qada + Mephilia.
Im-smurfing-possible. Qada opens with fire weak, Ominas wipes you out with Firaga dealing 7000+ damage and any of your party members who still miraculously survived are killed by Mephilia doing 9999 damage with Promethean Fire. Qada's fire weak ignores having equiped Fire-nullifying equipment like shields. Even with dual wielding blood-shields and all M-Defence buffs, absorb M-Damage and Barrier Shrouds, they wipe the floor with you in one turn. Reflect rings? Qada's Fire Weak ignores that and Mephilia's Promethean Fire does, too. Auto-shell? Does jack-smurf, Ominas and Mephilia's damage combined still murders you. And this is all before Yuliana can even begin pummeling you with comet.
There is not a damn smurfing thing you can do to win this fight. It is impossible. The game basically cheats. You're dead in one frigging turn, no matter what you do. I'm all for challenge but this is bulltrout. Bull. Trout. With capital B and T.
Smurf this game.