The unique cost makes this pretty hard to judge, but the card looks hugely overpriced for at least 2-4 player games. In 2 player, it's a $4p which plays you possibly one card out of probably very little choice that was one that fits your opponent's strategy and not necessarily yours. I think that effect might be acceptable as a $4, it's certainly not a $4p. In 3 player, suddenly you have something about as valuable as a King's Court - probably more actually - and it's letting you play up to two cards. This would probably be okay as a $5. Still bad. Four player, it's more expensive than a Province, and the effect is... now actually probably worse, because engines are harder to build in 4 player games, so there's a good chance this misses a few players.
The blocking effect seems very tacked on, it really doesn't seem necessary for the card. The card isn't an attack in any way, so doesn't really need something to stop it (it would be like Tribute having a clause that if the player to your left revealed a Tribute, then they only revealed one card from your deck).
I think if you fixed the cost at $5 and removed the reaction, then you might have something pretty reasonable. Maybe even $4 would be better - it gets crazy in 5-6 player, possibly, but so do Thief and the like, and it's poor in 2 player still.
