Instant, 1G (2)
Common
Transform all Humans. Prevent all combat damage that would be dealt this turn by creatures other than Werewolves and Wolves. (Only double-faced cards can be transformed.)
Illus. Ryan Yee

9/22/2011: Moonmist causes any double-faced Human to transform, not just Werewolves.
9/22/2011: Whether or not a creature is a Werewolf or a Wolf is checked only as combat damage is dealt. If the creature isn't a Werewolf or a Wolf at that time, its combat damage will be prevented.
9/22/2011: Moonmist will prevent combat damage dealt by a creature that isn't a Werewolf or a Wolf even if that creature wasn't on the battlefield (or was a Werewolf or a Wolf) when Moonmist resolved.
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