On the eastern side of the southern continent, just before a large subcontinent covered in mountains, lies this Imperial outpost. "The Empire "Gestahl"" plays.

And they leave to regroup.

And she leaves to get backup.

The lack of soldiers is indeed odd, especially since the place was crawling with them earlier. It's almost as though they want... nah, couldn't be. Anyway, the only interesting place here is the basement of the lone building, and that's locked, so just go on through to the other side.

Beyond the outpost is a swelteringly hot cave. "Another World of Beasts" plays.

Most of the enemies here absorb Flame and are weak against some combination of Ice, Water, and Holy, so take advantage of that. Mog's Water Harmony tends to work well, though he may need a few tries to get it started thanks to the terrain mismatch, so you might have better luck with a Trident, optionally combined with Wyrmknight's Boots for double damage. Gau should favor the Chimera Rage for Aqua Breath, while Mash's Aura Cannon works well against the frequent undead monsters. Tina and Lock can use the Icebrand to good effect, as can Edgar, though he's better off using his Machines. Wear Earth Garb where possible to protect against Lifeshaver, a draining attack some of the enemies like to use.

The third room has a series of bridges over lava that periodically switch between two layouts. Watch the pattern carefully before moving to avoid falling in, which inflicts damage and sends everyone back to the beginning of the room.

Don't miss the Ultima Weapon in one of the side caves. It's not especially impressive just yet, but it does ignore defense, and the damage increases unusually quickly with rising levels, as long as you keep your health up. Unless used with Mug, in which case a bug causes it to act like just a normal weapon, but with 255 attack power, which isn't bad at all. Get it now, while you can. Step on the button on a raised floor to open the cave, which also contains an Ether Turbo and two Magicite Shards.

Other treasures of note include an Assassin Dagger in the first room, a Kazekiri Blade in the second, an X-Potion and Heiji's Truncheon in the moving bridge room, and two Ether Turbos, an Elixir, a Genji's Bracer, and a Magicite Shard in the large cave. Not bad, but don't try the Assassin Dagger on the undead monsters.

Hitting a certain switch drops a Ninja on the party. Beat him up. Instant death works well.

The large area below a long staircase has a number of hidden items, mostly ninja scrolls. Walk around pressing A to find them.

Unfortunately, the messages for the items found aren't entirely accurate in either version of the game. Even more interesting is what isn't here. Several of the lines for items found go unused, including one particularly unusual one:

Literally a discared cicada skin, utsusemi also serves as the name for a ninja evasion technique (as in the Ragnarok Online skill Cast-Off Cicada Shell), suggesting that a ninja scroll may have been removed or renamed during the course of development.

Eventually, the party comes to the bridge leading to the Mystic Barricade. The music stops as lightning strikes dramatically.

Tina steps forward, but hesitates... and an unfortunately familiar laugh interrupts. 1-25 "Metamorphosis" plays, though it's perhaps overly dramatic.

Switch to a combat screen with Cefca and the non-Tina characters.

Combat ensues. Cefca's combat script has some interesting things, like randomly counterattacking and using healing items after every few hits he takes, but none of that matters. Whether by design or oversight, hitting him with anything (even a healing spell!) will end the battle immediately.

End combat. Stop music. Tina glows a few different colors, then turns Genjuu to glow a few more colors.

The gate opens, and the screen shakes violently. Back to a combat screen.

Everyone hits the ground as several Genjuu rush past. "Metamorphosis" resumes.

Cefca is blown away. Excellent.

Tina falls into the scene, back in human form...

...then collapses. Not so excellent. Exit combat screen, and the music stops, but the shaking continues.

A rockslide blocks off the gate.

The party leaves the room with the gate to find a new passage that serves as a shortcut to the entrance. There's no going back to the gate, since the party refuses to, not that there would be any point to it regardless.

Make sure you didn't miss anything. This is the best time to explore the cave, and it won't be accessible at all before long.

A representative of the others meets them on the way out of the Imperial base.

If I'm reading the event script correctly, the priority is: Lock, Cayenne, Edgar, Mash, Setzer. Since the party must contain Tina and can therefore hold no more than three other characters, that means Setzer will never fill this role, since there will always be a character not in the active group who takes priority over him.

The following lines appear in this section of the game data but appear to be unused.

Soon after.

Switch to combat screen. "Metamorphosis" plays again.

Something flashes.

He tackles her as one flies past.

He tackles Setzer as another flies past. More pass by, and the screen shakes and turns red.

Cutscene of the airship losing control and making a crash landing. The party comes to on deck.

Most characters now have new lines when not in the active party:

怒ってた (okotte ta, were angry) makes far more sense than 起こってた (okotte ta, had happened) for this line.

Again including some who can't even be here:

Anyway, let's go take a look at Vector. The airship crashed near Maranda, so head northeast to get there.

Setzer has an unused line for this point in the game, configured to display when speaking to him by the table where the coin flip occurred, but he doesn't appear there anymore now that he's joined the party.