Rulings

• 2011-01-01
  If the targeted artifact or creature card leaves the graveyard by the time the ability resolves, the ability doesn’t resolve. The player won’t put any cards into his graveyard.
• 2011-01-01
  The converted mana cost of a card in a graveyard is determined solely by the mana symbols printed in its upper right corner. The converted mana cost is the total amount of mana in that cost, regardless of color. For example, a card with mana cost has converted mana cost 5. If the mana cost of a card in a graveyard includes , X is considered to be 0.
• 2011-01-01
  If the player has fewer than X cards in their library, they put all cards from their library into their graveyard.
• 2011-01-01
  The X in Geth’s activation cost must be exactly the converted mana cost of the targeted artifact or creature card. You can’t pay more than X to put more cards from the opponent’s library into their graveyard.