描述
A Rare upgrade card is an NFT that enhances an NFT Hero’s social status to the level of ‘Rare’ within the SIDUS universe. To upgrade to Rare status, the user needs an Original NFT Hero and 1 Rare upgrade card. Each upgrade card can only be used once. After the modification process, the user ends up with 2 NFTs - their Original NFT Hero and the upgraded, higher status one.
