Synthesis is a feature in the Star Ocean that normally complements Item Creation. Through Synthesis, players can improve their equipment by adding items which imbue Factors into the base weapon, armor or accessory in question.
Adding a factor to a weaponYou can add many effects to an item through certain types of invention like crafting and synthesizing. Below is an example of adding a factor to a weapon through synthesis. This should give you an idea of invention's vast potential.
Step 1: Select a Weapon
First, select the weapon on which you will base your invention. Any weapon can be used, but you should select a weapon that will be useful in battle.
Step 2: Synthesize the Weapon
Set a line in the workshop for SYTH. You must have the synthesis materials in order to execute this step. This will result in the reinvention of the weapon with the selected item's effect. If successful the new item will have -R# appended to the end, where # is the number of times the weapon has been synthesized.
Synthesis allows you to merge equipment with other items to synthesize even stronger equipment. More to the point, you can add effects and bonuses to equipment by merging them with other items such as Blueberries, Pickled Plum, Attack Card or other Equipment. Equipment available for synthesis include Weapons, Armor, Neck and Wrist Accessories.
You cannot synthesize Common Items with other Common Items.
Each item that can be synthesized has certain stat bonuses and factors that it bestows on the synthesized Equipment.
Stats - Stats include ATK, DEF, HIT, GRD, and INT. The 5 basic stats in the game.
Factors - There are many Factors in game, some include ATK +#%, HP DMG +#%, #% Poison Immunity, et cetera. Each Item has 4 Factor Slots.
Resistances - Resistances are the resistance factor for each of the 7 Elements. The maximum resistance factor is 20 (Full Immunity); 0 means you have no resistance to that element (Normal DMG); negative resistance means you receive extra DMG.
Adding Resistance is only possible by synthesizing an Equipable with another Equipable.
There are two items in each Synthesis, the first called the Base item and the second called the Synth.
Every synthesizable item has a Synth Limit which is displayed at the top-left corner in the Synthesis Panel. This number is how many times you can synthesize this particular item as the Base, each time you synthesize the item the Synth Limit of the Base is decreased by 1, when the Synth Limit reaches 0 the item cannot be synthesized as the Base item.
If a Synthed Equipable is used to synthesize with another Base, the Synthesis will copy from the Base of the Synth item.
For Example: If you synthesize a Blessed Sword (ATK 36) with a Workman's Blade (ATK 22), you receive a Blessed Sword-R01 (ATK 38).
Similarly, if you synthesize a Workman's Blade (ATK 22) with Bizarre Fruit (ATK +4), you receive a Workman's Blade-R01 (ATK 26). If you then try to synthesize Blessed Sword (ATK 36) with Workman's Blade-R01 (ATK 26), you receive a Blessed Sword-R01 (ATK 38).
Notice you receive the same item in both instances. This is because only the Base of the Synth item is considered when Synthesizing Equipment.