How can I save Assasin?

Work through the floating continent area and find Kefka moving the three goddess statues out of alignment. Shadow will buy the party some time to escape and a timer will appear in the corner of the screen counting down the amount of time left before the floating continent is destroyed.

Run through the floating continent until u reach the edge and an option will appear to jump on the airship of leave. Choose the option to wait. When the time is almost out Shadow will reappear, kom bij the party and be in the world of ruin.