MySql 5.7

SELECT
    w.id,
    wp.age,
    w.coins_needed,
    w.power
FROM wands w
    JOIN wands_property wp ON wp.code = w.code
WHERE wp.is_evil = 0 AND w.coins_needed = (
    SELECT
        MIN(coins_needed)
    FROM wands derived_w
    JOIN wands_property derived_wp ON derived_wp.code = derived_w.code
    WHERE derived_wp.age = wp.age AND derived_w.power = w.power
)
ORDER BY w.power DESC, wp.age DESC
;

USING MS SQL SERVER BECAUSE MYSQL WOULD NOT ACCEPT ANY FORM OF CTE:

WITH cte1 AS (SELECT w.id AS cteid, wp.age AS cteage, w.coins_needed AS ctecoin, w.power AS ctepower FROM Wands w LEFT JOIN Wands_Property wp ON w.code = wp.code WHERE wp.is_evil = 0),

cte2 AS (SELECT wp.age AS cteage, MIN(w.coins_needed) AS ctecoin, w.power AS ctepower FROM Wands w LEFT JOIN Wands_Property wp ON w.code = wp.code WHERE wp.is_evil = 0 GROUP BY wp.age, w.power)

SELECT cte1.cteid, cte2.cteage, cte2.ctecoin, cte2.ctepower FROM cte1 RIGHT JOIN cte2 ON cte1.cteage = cte2.cteage AND cte1.ctecoin = cte2.ctecoin ORDER BY cte2.ctepower DESC, cte2.cteage DESC;

With Cte as (select WP.age as Cte_Age, min(W.coins_needed) as Cte_Coins,W.power as Cte_Power from Wands W left join Wands_Property WP on W.code = WP.code where WP.is_evil = 0 group by WP.age, W.power ) select max(A.id) ,Cte_Age,Cte_Coins,Cte_Power from Cte inner join Wands A on A.coins_needed = Cte_Coins and A.power = Cte_Power inner join Wands_Property B on B.Age = Cte_Age where B.is_evil = 0 group by Cte_age,Cte_Coins, Cte_Power order by Cte_Power desc, Cte_Age desc

With Cte as (select WP.age as Cte_Age, min(W.coins_needed) as Cte_Coins,W.power as Cte_Power from Wands W left join Wands_Property WP on W.code = WP.code where WP.is_evil = 0 group by WP.age, W.power ) select max(A.id) ,Cte_Age,Cte_Coins,Cte_Power from Cte inner join Wands A on A.coins_needed = Cte_Coins and A.power = Cte_Power inner join Wands_Property B on B.Age = Cte_Age where B.is_evil = 0 group by Cte_age,Cte_Coins, Cte_Power order by Cte_Power desc, Cte_Age desc