Various Fragments
Fragments are small pieces of an individual item which when the require amount is acquired, will fuse into that respective item (Be it spells, rings, or equipment and even NFS buildings).
Fragments can be obtained from Adventures (Seal, Crusade, Conquest), Arena, Alliance Battles and special events and promotions.
Fragments are the only way to fuse Not-for-sale items such as the Holy Ring, Challenge Abyss boss-rings, and Void Blast and Ice Drill spells. While they can be sold, they sell for less than the price of the item they fuse.