I thought to share my little experience with the acquiring of this Blue Mage spell.
I had set up a learning party for Level 5 Petrify, and it was pretty slow at first. The first time we killed the Manor Sentry before it used the spell. The 2nd through 4th times we let it use it once, then killed Lady Amandine when we failed, but then on the 5th run, one of the BLUs had an idea. Since we needed to learn the spell from the Sentry Manor and not the boss itself, should we kill the Sentry and not learn the spell, we would Self-Destruct and try again. It turned out that it worked, we had to Self-Destruct twice before learning it on the third try.
Self-Destruct was more useful than I thought it would be, I'll be sure to try to think outside of the box when considering these spells. They kept Blue Mage true to its nature of having its spells situational. Well done.