*The trick is to do the Enhancement Quests or Summon Quests (except for the Premium Quests).

1) If a Cactuar appears during the x9 battle, finish the battle and keep the extra rewards.
2) If it doesn't appear, go to the menu and click on "retire."
3) Repeat the same mission, but this time set Stamina to "Unused" to do a single run.
4) Finish the run with "Unused."
5) Start again from step 1).

(It works with x3, x6, and x9)






I hope this helps! :)