Magic gems, magic duel and returning

[LDiCesare]

I'm trying to do the following with an S9 mage:
Cast teleport, script Magic Duel x 3 + Returning (cost: 5 gems).
I give 6 gems to my mage.
End result: The very first magic duel uses 3 gems, which means, the mage will be unable to finish the script. I suppose giving him 12 gems might cut it, but it's kind of inefficient.
Is there any way to coerce a mage into doing what the scrit says?

I mean, the ai could read the script, check the number of gems required, and make sure it doesn't shoot itself in the foot on first turn of the battle.