The only time in Final Fantasy III you can get Mog’s Water Rondo Dance is in the World of Balance. First you must recruit Mog in your party. Go to Narshe and find the treasure house to the South of the house Terra woke up in the beginning of the game.
You will see a cut scene of a thief name Lone Wolf emptying one chest. Follow Lone Wolf to where the Tritoch esper is on the edge of the cliff. You will have a choice to save Mog or get the treasure that Lone Wolf stole “Gold Hairpin”. The obvious choice should be to save Moogle.
Now it’s time to get the Water Rondo! Go to the Cave of the Veldt (Where you found the Scuba Helmet). Make sure you have Mog in your party (Alive) or you will not learn the dance. Now jump in the Lete River and Serpent Trench and start battling. You will receive a message saying “Mog learned Water Rondo Dance” after the battle.
Water Rondo Dance MovesWild Bear – restores hpSpecter – confuses opponentEl Nino – heavy damage on all opponents (water elemental)Plasma – attacks single opponent (lightning elemental)
Congratulations you have learned Mog’s best dance. The only time you can perform the dance without messing up is when you fight in Lete River or Serpent Trench. Since these places are only available in the World of Balance Mog never has a 100% chance of success for Water Rondo. Keep that in mind for do or die battles.