Level of the card in your team caps the stats of the cards that you use in Battle Days.
•        Card stats never go below the Friendly Levels: Level 4 for Common cards, level 3 for Rare cards, level 2 from Epic cards and level 1 for Legendary cards. So if you have a card at a level lower than Friendly Level, you will use it at Friendly level.
•        If level of the card in your collection is higher than Team Level, you will use it at Team Level.