After using magic is used, use controller two to match the arrows that appear at the bottom of the screen. If all are matched correctly, you will get more magic damage.
Fighting agains Titans
When you start to fight a Titan, have a party member cast Bait then move them to the bottom center of the screen so that they are behind a rock. The Titan will walk up to the rock and just stop there. Have the rest of your party cast Magic on the Titan for an easy win. If you do not have enough Magic to defeat the Titan, buy some MP Recoveries, and Magic Might at a gem shop. This may take awhile, but will give you great rings.