Quote Originally Posted by Rand Al'Tor
IIRC, someone suggested that it might be the Junction Machine Ellone Ultimecia uses to compress time.
Junction Machine Ellone is a device for sending one's consciousness into the past to possess someone else. It bascially re-creates Ellone's ability. Time Compression is a form of magic.
Scanning Ultimecia's final form reveals that she has 'transformed to absorb all space and time', or something along those lines.