There are two major problems I have with this card. One of them is the 'attack the attacker' thing. But ok, if you really like that, roll with it. The other is that it's basically worthless without attack, and actually not that strong with them either. Heck, you could cost the thing at 3, and I still think I wouldn't like it all that much.
I mean, you're paying 7 to destroy their card that costs less than 7. In the meantime, this card is not that useful to you. And they get at LEAST one play out of it before it's destroyed. Ergo this card is super weak.