Let users know that card is not final draft?

In a card game I've developed I want to add something that makes it clear that the cards are not a final revision, and that it may change?

I was thinking about water marking the entire card with 'draft', but it doesn't look fantastic.

Here is a quick example i've knocked up just to play-test the game.

Please note that the image does not belong to me, and the text is just a 'fun' placeholder.