This could be really fun with a card that hides the nature of cards in play (e.g. something that lets you flip a card in play face down so you're enemy cant see what it is) That would make for a very useful anti-CC / anit-PC combo.
This is also cool because there is a good reason for both the unupped and upped version to be in a deck at the same time (e.g. one makes copies and the other shuffles them around to protect them)
I think the mirror images should last a little longer though.
Good idea, I might add that in my -on series for Aether.
The mirror images last one turn per spell, as to make it not too overpowered.
