It's possible that:
* Fan-made: Someone might have created a custom card with Ben 10 imagery, but it wouldn't be an official card.
* Misunderstanding: You might be thinking of a different card that has a similar name or theme, but it's not directly related to Ben 10.
If you can provide more details about the card you're thinking of (e.g., its name, picture, or the effect it has), I might be able to help you identify it.