Wording on this is a doozy. Rewordings should at least double decipher spells.

"Whenever you cast..." Why are you restricting this to casting copies? Other than cipher and decipher (poor choice of name there too), only 10 cards allow you to cast a copy. Also, there's nothing black about this; blue/red get copy effects, but this could be mono-blue.

I was really confused about what this is supposed to do, but if it's designed to combo with decipher, that makes sense. It would be nice if it could trigger off "copy on the stack" as well. If so, maybe it would be mono-blue?

It might be better if it gave a bonus other than "copy" just so it was a bit less confusing, even though the copy is thematic.

ETA: Ah, this was supposed to be a gold build-around uncommon for decipher. That does make sense! But the card itself was confusing. The other comments still apply, but obv there's good reason to keep it UB and reference decipher.

The intent of this card was to always be a "cipher/decipher enabler."

The problem with "copies on the stack" is that it just combos with itself as those would make copies, hence the "on cast" wording.

Black has "can't be blocked" on occasion. Blue has it too, but I want this to explicitly encourage you to go . I hesitate to add more text to this, but a quick keyword or activated ability to make it more black could help. Alternatively, shifting this to blue seems totally fine, though the name might want a tweak.

How about "If you would copy a spell one or more times, you may copy it one additional time. If you do, you may choose new targets for it and cast it without paying its mana cost." I chose this wording so it wouldn't break with itself or with multi-copiers like storm.

With the colour, I was thinking more, if this was U, it can act as a lord for other copy effects as well, and it's always good for the card to have multiple uses. I think it's acceptable as UB if there's a reason for that, if it combos with a UB mechanic, even if it wouldn't normally be in those colours.

If you wanted to make it more clearly black, it could be "Menace" instead of "Can't be blocked"?

Alternatively, maybe decipher is U and a different other colour this set, not B?

Ah, I see your point. I thought it was better to decide what the card SHOULD do, and only change that if you were absolutely certain it can't be templated. But I agree, the wording for "cast a copy" AND "copy on the stack" is looking clunky :(

Normally I would consider menace. However, I have put menace on an inordinate number of cards, particularly for

Flying? And maybe then being a vampire or other race rather than a human.