2011-06-01 : If the card has an X in its mana cost, you must choose 0 as its value.

2011-06-01 : If the card has any mandatory additional costs, as Kuldotha Rebirth does, you must pay them in order to cast the spell.

2011-06-01 : If the card you look at isn’t an instant or sorcery card, it remains on top of your library. You don’t reveal it.

2011-06-01 : You may pay additional costs, such as kicker costs, of the instant or sorcery card.