Enchantment, 1WW (3)
Rare
As Nevermore enters the battlefield, name a nonland card.
The named card can't be cast.
"By the law of Avacyn, the following thoughts, words, and deeds are henceforth disallowed."
Illus. Jason A. Engle

9/22/2011: No one can cast spells or activate abilities between the time a card is named and the time that Nevermore's ability starts to work.
9/22/2011: Spells with the chosen name that somehow happen to already be on the stack when Nevermore enters the battlefield are not affected by Nevermore's ability.
9/22/2011: Although the named card can't be cast, it can still be put onto the battlefield by a spell or ability (if it's a permanent card).
9/22/2011: If you want to name a split card, you must name both halves of it (for example, "Boom/Bust"). Neither side of that split card (Boom or Bust) can be cast.
9/22/2011: If you want to name a double-faced card, remember to name the front face of that card. (The back face can't be cast anyway.)
9/22/2011: The named card can be cast again once Nevermore leaves the battlefield.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Extended (Type 1.X)
Legal in Standard (Type 2)
Legal in Classic (MTGO)
Legal in Commander
Legal in Modern