Hearthpwn

You don't know how good this is til you play it on turn 1 with the coin in hand.

Love it! Powerful, but not your standard turn 1 drop. 

This is more dangerous than it looks, it enables running cards like Zephrys the Great in decks with some duplicates. Instead of becoming a dead card in your hand until late game, you just put it back in the deck and potentially it will show up again when its enabled

This card will belong in 80% of decks. Literally best card in whole expansion.

Card set, not expansion.

I'm not sure what deck this belongs in, but it seems good in and of itself.

If it’s a minion, would it keep any hand-buff effects.

iirc nothing that gets shuffled into your deck ever keeps buffs.

This, except for special exceptions like this: Immortal Prelate or Kingsbane.

Also, corrupting a card effectively transforms it into a different card, so those stay too. 

Cool card!