Voice: It seems Master Golbez has underestimated you.
Mars: The Lord of Wind, Barbariccia!
Barbariccia: You disappoint me, Mars. Submitting to a weak imbecile, despite all your powers.
Mars: I've simply come to my senses. I've grown sick of siding with animals like you!
Barbariccia: You snotty little wretch. I'll enjoy killing you all! With the old man and his Meteor gone, you stand no chance.
Mars: Let's see about that.
A gust of wind spirals around, gathering around the party...
Tornado, tornado, she's the lady who calls storms... almost naked.
Barbariccia hits with fierce physical attacks. Since Aero-Aerora-Aeroga aren't established series spells yet, she's fond of Ray and Tornado. Tornado we're familiar with, Ray causes slow petrification.
Her other trick is to summon a whirlwind around herself. In this form, the battering gusts knock away all physical attacks, giving her perfect evasion against swords, hammers, spears, claws, and arrows. Barbariccia then counters with Maelstrom, a party-wide Tornado spell that drops everyone to single-digit HP. Needless to say, that's a problem... but without a black mage in the party to blast her with magic, what can you do?
I've no idea why Mars has vanished from this screenshot, because she just hit Barbariccia with a leaping attack. While the tornado covers Barbariccia's body, her head is sticking up out of the top of the funnel cloud, so a decent Jump attack can hit her where she's not protected.
As TA points out, the Blood Lance is horribly inaccurate and misses even this crucial attack. I had just chalked it up to the tornado barrier making the attack miss even as Barbariccia is knocked out of it, because switching back to his starting equip also missed.
This knocks her out of the tornado form, allowing everyone to continue attacking.
Of course, keeping her from hitting so often is not a bad use of Friday's time.
It's a complex battle that puts you on the defensive for most of the fight -- recovering HP from Tornado or her physical hits, healing slow-petrify from Ray, and timing your attacks so as to not provoke a Maelstrom counter...
But eventually we are victorious.
Barbariccia: Regardless, you'll never leave here alive! Hahahaha!
Brent: It's collapsing!
Mars: Dammit!
Niku: That bastard!
Friday: Hold on to me!
As Barbariccia's deathtrap collapses the Tower of Zot, Friday warps everyone to safety.