Save, then trudge through the numerous save points that appear. Head for the door in the background.
The party will have to combat a slew of low-level sorceresses from each era. Every fight takes place on a different battlefield, culminating in a showdown with the final Sorceress.

BOSS >> SORCERESS C
HP: 50,000+ Weakness: ? Strength: ?
AP: 55 Draw: Flare, Holy

Strategy: She can hit you pretty hard with a single counterattack, taking away roughly 1,000 HP from one character. When she finishes her countdown, she’ll unleash Ultima on the party, something you don’t want. Hit her with a Meltdown, Aura-Renzokuken combo and have the remaining cast heal or summon powerful GFs such as Bahamut and Eden.