and from the monk entry: Perfect Self: At 20th level, a monk becomes a magical creature. She is forevermore treated as an outsider rather than as a humanoid (or whatever the monk’s creature type was) for the purpose of spells and magical effects. Additionally, the monk gains damage reduction 10/magic, which allows her to ignore the first 10 points of damage from any attack made by a nonmagical weapon or by any natural attack made by a creature that doesn’t have similar damage reduction. Unlike other outsiders, the monk can still be brought back from the dead as if she were a member of her previous creature type.
more
Perfect Self: At 20th level, a monk becomes a magical creature. She is forevermore treated as an outsider rather than as a humanoid (or whatever the monk’s creature type was) for the purpose of spells and magical effects. Additionally, the monk gains damage reduction 10/magic, which allows her to ignore the first 10 points of damage from any attack made by a nonmagical weapon or by any natural attack made by a creature that doesn’t have similar damage reduction. Unlike other outsiders, the monk can still be brought back from the dead as if she were a member of her previous creature type.