Magic Storm - Character Deck effect.

Maximum critical damage from thief set and defense ignore from pirate set are the best sets in my opinion.
If you can do sufficient damage on each hit (average 533k at 100% crit, higher for lower % crit) then the thief set can surpass Mage set with 100k MP (~600k+ crits seems more realistic than 100k MP), and pirate set will probably be better than thief set at any place you don't 1hko unless you already have 100% ignore def or very close to 100%.
On the other hand simply using whatever individual effects you like best might be better due to lack of good choices if you need 3 thieves/mages/pirates.