2 Rewards Cards need to be fixed before they finish they print period can be unlocked and put them to sell this cards are: Venari Marksrat and Fungus Flinger, I'm sure everyone is aware of the main issue, this cards are a lot better at level 1 than in any other level in most of cases because of his low hp even if you has trying to keep this card at level 1 you will get the golden one that has a higher level.
What do you think will happen when this card is available for sell, well everyone will want to get rid of his golden ones and his level up ones and each player will only want to buy a single bcx, getting the lowest price it can have according to his burn value, this will drag down in price the others rewards cards, it may not sound too relevant but it will cause some issues on the economy that can be easily avoided also think is no good at all have a card that is better at level 1.
Easy Solutions:
Modify the card: either make it keep the same hp from level 1 to max or gain the Martyr ability when it reach his max hp around level 3 - 4.
Enable level selection on all cards: This was announced for the team long time ago that will be able to select a previous level of a card to play.
This second options is something but it does not fix all the problems the first option will be better.