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.)
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.
Moonmist causes any double-faced Human to transform, not just Werewolves.