Instructions
Collect synthesis items during normal battles and from chests throughout the world.
Enter your ship once Sarah has joined your party. Go to the terminal and select "Synthesis."
Choose the armor or accessory you want to add a resistance to. There are four slots on every piece of equipment that you can add items to. Synthesis items will say what they are resistant to in the item menu, either earth, fire, water, thunder, wind, light or darkness. Select which synthesis items you want to equip and equip them.
Open the equipment menu and put the resistant armor and accessories on your party members. Your characters will absorb some or all attacks without taking damage when you fight a battle with an enemy who throws certain elemental attacks.