Animate Library (UST) from Unstable, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Raymond Swanland
• Card Text:
  Enchant your library
  Enchanted library is an artifact creature on the battlefield with power and toughness each equal to the number of cards in it. It's still a library.
  If enchanted library would leave the battlefield, exile Animate Library instead.