Yeah there is, although some have argued that it was deliberate on Square's part.
Here it is:
The first Dragon Zombie your party meets in the right path can cast Pandora's Box as a last resort when it's mortally wounded. Every Dragon Zombie you meet after that doesn't use Pandora's Box. Period.
I fought over 200 of them before I found out about this. So save before you try to get Pandora's Box.
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