The simplest way of making 12 DimDecks impossible is to just put a stipulation on the card that states "Does not replicate Miss chances".
Yes, but wouldn't this make it unable to produce any Dim Shields, Fogs, Dusks, Wings? Also, having the ability to produce any type of shield more than once may buff 60-card rainbow stalls A LOT, so I think a restriction like this must exists, shouldn't it?
For Morphing Shield, you do not need the "unupgraded" in the text. Just by typing in "shield" we already associate it as being unupgraded. Take the Shard of Serendipity as an example.
I will think about this change, thank you, but I prefer my text to be clear, like Mummy's, Skeleton's, Fate Egg's, Pharaoh's text where is a difference between 'cards' and 'elite cards'.
EDIT: I understood what you meant and you're right, even my Mummy/Skeleton/FateEgg/Pharaoh examples work like you mentioned, I will do that change as soon as possible, thank you!
EDIT2: I've added a new rule which prevents Morphing Shield to create each shield type more than once. Ready for the crucible.