Dunno, but "and can block creatures as though they could be blocked" sounds redundant if it can already block unblockable creatures. Maybe make it "can only block unblockable creatures as if they weren't unblockable."

I'm pretty sure this actually wants to have, as its entire rules-text:

"Shadow"

And then I'm equally sure that shadow was a bad idea.

Oy vey. For more on this subject, see Knight of the Periphery. The end result of that discussion that eventually went on the message boards is that 'unblockable' isn't really something you can call out in the rules. It also causes headaches when one thinks of the fact that Anaconda is 'unblockable' if your opponent controls a Swamp (it says so right in the reminder text). Oh, and is an unblockable creature really unblockable when it isn't attacking, during your turn? Are the rest of your creatures during your opponent's turn 'unblockable' by virtue of the fact that they can't attack, and therefore can't be blocked?

So, yeah, it gets weird. Personally, I think this sort of interaction should be allowed to happen, but it does require an overhaul of the rules on the subject (turning 'unblockable' into a proper keyword. They should probably do that with indestructible, too, and stop being so cute about 'words that act like keywords but is just proper grammar').

Comp rule update: Unblockable (This creature can't be blocked.)

Landwalk (Whenever this creature attacks, it gains unblockable until end of combat if defending player controls a land.)

What other abilities reference unblockability, I'll fix them too!

Ha! Take that Comp. Rules!

I still think this leads to the whole problem of Shadow.

Still, I can't begrudge you wanting to be able to do SOMETHING about the proliferation of unblockable creatures. It seems more common than flying, these days.