select w.id, wp.age, w.coins_needed, w.power
from Wands w
join Wands_Property wp ON w.code = wp.code
join (
    select age, min(coins_needed) as min_gold, power
    from Wands w 
    join Wands_Property wp ON w.code = wp.code
    where is_evil=0
    group by wp.age, w.power
) as sub ON wp.age = sub.age AND w.power = sub.power AND w.coins_needed = sub.min_gold
order by w.power DESC, wp.age DESC;