Polymorph

Sorcery, 3U (4)
Destroy target creature. It can't be regenerated. Its controller reveals cards from the top of his or her library until he or she reveals a creature card. The player puts that card onto the battlefield, then shuffles all other cards revealed this way into his or her library.
Illus. Robert Bliss

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: If there are no creatures in the player's library, then the target creature is still destroyed, you see all the cards in that player's library, and then they shuffle and continue play.
• 10/1/2009: If the targeted creature is an illegal target by the time Polymorph would resolve, the entire spell is countered. Nothing else happens.
• 10/1/2009: If the targeted creature is indestructible, it's still a legal target -- it just isn't destroyed. The rest of Polymorph's effect happens as normal.
• 10/1/2009: If there are no creature cards in the player's library, all the cards in that library are revealed, then the library is shuffled. (The targeted creature remains destroyed.)
• 10/1/2009: A "creature card" is any card with the type Creature, even if it has other types such as Artifact, Enchantment, or Land. Older cards of type Summon are also Creature cards.

Format Legality	Legal in Vintage, Legacy, Extended, Standard, MTGO Classic
Printings (4/32)	Magic 2010 (Rare) Ninth Edition (Rare) Classic Sixth Edition (Rare) Mirage (Rare)