Synthesis is a feature that allows players to upgrade Heroshards, Runes, and Runeshards to get 1 NFT hero, a higher level rune, and a rune level 1 respectively. Before synthesis, players must also use $ES as a fee. Furthermore, not every synthesis will be successful; some may fail. On the other hand, every time a player fails to synthesis, they will have a better chance of succeeding the following time. Furthermore, the amount of material you used for synthesis will increase following each failure.