Lucky Dice is a leadership bonus ability. It has the following levels and effects:

  1. Ally Critical rate 10% up
  2. Ally Critical rate 15% up
  3. Ally Critical rate 20% up
  4. Ally Critical rate 25% up
  5. Ally Critical rate 30% up

Lucky Dice seems like it would be a good skill but Advance is probably a better pick. Critical attacks yield only 1.5x damage. Assume a group of monsters deals 100 damage per strike. A 20% bonus to damage yields a consistent 360 total damage. A 30% boost to critical yields (maybe) 350 damage per round. It may be possible that criticals affect the frequency of other monster skills but there is no indication that this is true.