Lists by ID all Creature-type cards with legal status.
legal status refer to status = 'legal'; Goblin-type cards refer to types = 'Creature';
SELECT T1.id FROM cards AS T1 INNER JOIN rulings AS T2 ON T1.uuid = T2.uuid INNER JOIN legalities AS T3 ON T1.uuid = T3.uuid WHERE T3.status = 'Legal' AND T1.types = 'Creature'