Some things to consider when making card ideas:
Does it accurately reflect the Bible? (An evil card with reference of John 3:16 is probably not well thought out in this area)
Is it overpowered? (Is it a card that gives you many benefits with no costs, and no way for opponent to stop it?)
Is it practical? (would anyone use it?)
Is it unique? (would everyone use it?-this is probably bad in most cases)
If you go through these questions each time you design a card, you'll probably be able to better iron out problems.
*Credit goes to Professor Alstad, I just put this in a separate post for easy reference and maybe stickitude.
Further guidelines to consider:
We already have many cards representing God, Jesus, and Satan. If you post an idea for making any of these cards, expect sharp criticism.
Verses are found in the bottom area of a Redemption card. You cannot fit the entire Bible into that space. Therefore, making a card with a reference from the whole Bible is probably not a good idea.
If someone makes a different version of a card that has been made before, reminding them that it has been made before doesn't really help anyone. Just remember: Ram's Horn.