SELECT w.id, cheapest_wands.age, cheapest_wands.coins_needed, cheapest_wands.power
FROM Wands w
JOIN Wands_Property wp
    ON w.code = wp.code
JOIN 
    (SELECT 
        wp.age,
        w.power,
        MIN(w.coins_needed) as coins_needed
    FROM Wands w
    JOIN Wands_Property wp
        ON w.code = wp.code
    WHERE wp.is_evil = 0
    GROUP BY wp.age, w.power) AS cheapest_wands
    ON wp.age = cheapest_wands.age AND w.coins_needed = cheapest_wands.coins_needed AND w.power = cheapest_wands.power
ORDER BY cheapest_wands.power DESC, cheapest_wands.age DESC