When the NFT is eligible to enter the Evolution Zone (character reaches level 30 or 70), the player needs to use some GDC/HLS as a fee. They also need to use another NFT (with the same rank) as the material to evolve NFT.
It also has the same meaning as NFTs cannot go to the next level if they are not trained.
Because evolution will still have a failure rate, the "Fee" will be lost, but the materials will be kept.
The "fee" for upgrading the NFT will be increased by level, as detailed in the table below:
Lv30: X amount of GDC/HLS, 1 NFT with same rank (any level), 75% rate.
Lv70: X amount of GDC/HLS, 1 NFT of the same rank (any level), 50% scale.