Spoilers Revenant Wings mission 8-4 HELP!!! Spoilers

[NGU]

Spoilers:
Ok I am stuck I have most Espers with the expetion of those aquired after chapter 8 and I am still stuck my Party Is Basch Balthier Vaan Penelo Llyud. I beat chaos then Mydia pops outta nowhere with her cool armour and i clear out the espers then go for her full out assault and do barely any damage. I hit her with pyroclam I forty my espers mind u balthier is starting to annoy me with his slow mist gathering capabilities but I need A good stratergy HELP.

[qwertysaur]

Use Mateus as your rank III esper, and make one of your rank II espers Carbuncle. Mydia is a melee type, so Mateus should be the most effective. Also switch out Basch for Kytes, as his magic is really helpful against all of the espers Mydia brings out. Summon Mateus with Vaan or Kytes so their mist charges up during the battle. When Mydia appears send Mateus after her after all of the espers she summons are gone. When Mateus falls summon him again from the closest summoning gate to keep Mydia busy. Lamias will keep coming from the bottom of the screen, and bombs from the top, so keep all of you other espers and characters where Chaos was in the beginning. Make sure you capture all of the summoning gates, and if Mydia starts to attack your main party, send some espers to keep her busy. Use quickenings when you get them for some extra damage. You will need to summon Mateus many times during the battle, because Mydia does a lot of damage.

[Dragonsoul]

I posted an in depth answer in one of the threads here(or the FF XII forum on ffshrine.org), check for it.