22 Sept 2011
If you have two or fewer cards in your library when the ability resolves, all of them will be put into your graveyard. Heretic's Punishment will still deal damage equal to the highest mana value among those cards.
22 Sept 2011
The mana value of a double-faced card in your graveyard is the mana value of the front face.
22 Sept 2011
If all three cards have a mana value of 0, no damage will be dealt.
22 Sept 2011
If the targeted permanent or player is an illegal target by the time the ability resolves, the entire ability won't resolve. No cards will be put into your graveyard, and no damage will be dealt.