Rulings

• 2004-10-04
  The choice of creatures is made on resolution and not on announcement.
• 2004-10-04
  You can use mana abilities during the resolution of this spell if the player decides to pay the mana cost.
• 2004-10-04
  You choose whether to pay or not on resolution. If not, then you sacrifice the creature. You can choose to not pay if you control no creatures on resolution.
• 2008-04-01
  First the active player identifies the creature he or she controls with the highest mana cost (and chooses one if there's a tie) and chooses whether to sacrifice it or pay mana. Then each other player in turn order does the same. All creatures sacrificed this way are sacrificed at the same time.
• 2008-04-01
  Although Tariff checks the converted mana cost of the creatures on the battlefield, you need to pay the creature's actual mana cost (including color) to keep it on the battlefield.