Please list the donation messages of the donations for the projects created by a teacher working in a public magnet school in Brooklyn.
school in Brooklyn refers to school_city = 'Brooklyn'; public magnet refers to school_magnet = 't';
SELECT T2.donation_message FROM projects AS T1 INNER JOIN donations AS T2 ON T1.projectid = T2.projectid WHERE T1.school_city = 'Brooklyn' AND T1.school_magnet = 't'