It's not clear that it loses the +1 when it gets Enrage. The way it's worded implies that when it gets Enrage the +1 and -1 cancel each other out. It's obvious enough in context, because it would be overpowered otherwise, but I think it should have clearer wording.
I looked at this card originally and I thought, you know, it's a card, and you play this card. The card will be that card that you play so you're playing a card. So, it is one thing to play a card. If you're opponent doesn't really have any cards, the card will screw up the card pretty hard, and that means it's a pretty good card.