Sewer Nemesis (CM2) from Commander Anthology Volume II, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Nils Hamm
• Card Text:
  As Sewer Nemesis enters the battlefield, choose a player.
  Sewer Nemesis's power and toughness are each equal to the number of cards in the chosen player's graveyard.
  Whenever the chosen player casts a spell, that player puts the top card of their library into their graveyard.