What's the use of ice and fire fragments in Wulin legend? How come?

Ice and fire debris: First of all, we should complete the preface task of Ice and Fire Island. Pick it up at the Prime Minister's Office in Beijing. Until the task of the top deputy is completed. In this way, you can buy the special item "The Book of Five Elements" directly from the Secret Agent of Ice and Fire in Beijing, and then you can get the task in the new epic library from the Special Envoy of Ice and Fire. 10 series of tasks, step by step, constantly activate stronger challenges, make the task more difficult and gain more. Complete the white task and you will be rewarded with ice and fire fragments. Experience tasks reward ice and fire fragments, challenge tasks reward ice and fire hearts, and legendary tasks reward ice and fire essence! A certain number of ice and fire fragments can be pushed to the heart of ice and fire, and a certain number of ice and fire hearts can be pushed to the essence of ice and fire; Accumulate a certain amount of ice and fire fragments, the heart of ice and fire, and the essence of ice and fire, and exchange them for corresponding rewards at the ice and fire spy! Specifically, the convertible rewards include: gain state medicine, crystal attack stone, crystal life stone, crystal true spirit stone, advanced skill stone, condensed stone, mysterious attack stone, eternal life stone, ghost-killing stone, super gourmet pet, dawn YY stone, dream YY stone, sky-mending YY stone, crystal lens, rose perfume, supreme symbol, once-in-a-lifetime charm and never-falling charm.