I use Gem Box+Economizer+Quick to cast Ultima 4 times in one turn. Pretty obvious, instant 3997 damage, but then I have Gogo mimic for almost 8k damage in a turn for 4 MP total. Ow.

Also, I Imp Locke, give him Genji Glove, Offering, Titanium Helm, Imp Armor, and 2 Imp Halberds and he just PWNS.