Item Synthesis returns from Kingdom Hearts to Kingdom Hearts II. To synthesize items, simply locate a Moogle Shop, and under Buy and Sell you will find Synthesize. Once you enter the Synthesis Menu you automatically give up all of your Synthesis Materials and Recipes, of course if you have any in your Item Stock.Synthesis is the same as before, you need to locate certain items to synthesize different items for different results. It's also the only way to obtain the legendary weapons.