A bit too close to my Poison Trap (http://elementscommunity.org/forum/index.php/topic,26845.msg367290#msg367290), which is in Crucible at the current time. Difference is that it's just for this item, where mine is for any permanent on the owner's side.
Didn't know about yours
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Yours is more like the existing cards in this game, which really makes it mesh better. I thought of this card because I'd like to see more meta-game going on in elements. If you ever played MtG, morph kinda did something similar (bluffing what the card really is, that is).
Actually, maybe just a trap-type of card would be better. Something that is "face down" and is triggered by a specific condition.