Yes, you can upgrade your cards to improve their attributes.To have cards being upgraded within the game, it would be necessary to pay certain

amounts of Hertz tokens that are only able to be acquired by playing the game or buying from the marketplace. 

Once the user applies to have his card upgraded, the NFT is updated with the new attributes.  Utilize ’Hertz’, the in-game currency and you can

enhance the power of your favorite cards and create a formidable deck. My Card Collection