When you reacquire a class, Groa, or mount that you already have, you can synthesize them for a chance 

to get a different one of the same or higher grade. 

■ How to Synthesize a Class/Groa/Mount

 - Select a class/Groa/mount from the Menu list.

 - In the Synthesis tab, register 4 duplicates of the same grade to synthesize them.

 - Select Auto-select to automatically add them based on the grade you select.

 - Tap the Auto Synthesis button to synthesize all available grades.

■ How to Get and Use Synthesis Points

 - Starting with the Rare grade, you get Synthesis Points if you don't get a higher grade upon synthesizing.

 - Earn 20 or more Synthesis Points to get a higher grade as a reward.