Undercity Plague (GTC) from Gatecrash, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Vincent Proce
• Card Text:
  Target player loses 1 life, discards a card, then sacrifices a permanent.
  Cipher (Then you may exile this spell card encoded on a creature you control. Whenever that creature deals combat damage to a player, its controller may cast a copy of the encoded card without paying its mana cost.)