Don't you love the fact that a lot the spoiled cards have mistakes? Check the card spoiled in the article.
You'd say, given the fact the card is really simple (and really useless), it would be possible to avoid simple problems like forgetting what this card attaches to.
So yes. You play Dream Dagger, then it just stays there, because it doesn't attach like other powerhouses like .45 pistols. Then you try to activate it's ability and guess what? It doesn't work either, unless you can unattach a card which wasn't attached to anything.


