Funny Bug - Black Zombies and Plants
That's exactly what the title says. If you play a card fast enough, the minion on the field becomes darker that it normally is.
It works with plants too, and you can even have more that 1 at the same time.
What you need to do is to hover the card that you want to play over the lane you want it to be and drop it as soon as your turn begins.
(This is easier with zombies than with plants, because you can always time when your turn begins rather than being focused on when the enemy player ends their turn).
If you do it too early, the card will just return to your hand. If you do it too late, it will be as normal.
I think that the game uses the shadowy pic of the card that is shown in every card when it is not your turn or you don't have the resources to play it.
Nothing changes though. The cards still work as usual.
It is just a funny thing that I found and that I wanted to share.