Too much room for user error for us to pinpoint your bug for you. This board is for reporting bugs yourself, so you're going to need to be much more specific and bring a screenshot. As others have mentioned, there are dozens of reasons you could be taking damage past your Diss Shield/Field that are completely within normal game parameters.
Additionally, if there was an encompassing and devastating bug with a card such as this, it would've been fixed long ago. It would also be very well known and reported hundreds of times. In other words, it has to be specific and situational. The fact that no one knows what you're referring to yet points toward the likelihood of user error.