Treasure fragments are required to combine a treasure, and can be obtained through quests or battle. You must have atleast 1 of all the fragments in a treasure to start combining. Some treasures require 3 fragments, whilst others require 5. Below is a list of what treasures require what amount of fragments.

Panpipes - 3 fragments

Chariot - 3 fragments

Golden Fleece - 3 fragments

Golden Lyre - 3 fragments

Trident - 5 fragments

Magic Girdle - 5 fragments

Pandora's Box - 5 fragments

Aegis Shield - 5 fragments

Caduceus - 5 fragments

Horn of the Minotaur - 5 fragments

Once entering a battle for someone's treasure piece, you will be told the probability of you winning that treasure piece. For someone your level or some levels lower, the probability will read, "Probability to receive [treasure piece]." This is the standard probability. When battling someone of a higher level than you, it will read, "High probability to receive [treasure piece]." When battling someone a considerable amount of levels lower than you, it will read, "Low probability to receive [treasure piece]." This continues to decrease the higher or lower the level of the defender.