So if you each character gets one common and one legendary finisher and there are 17 legends, that means it costs 20400 Crafting Metals(Because 17 times 1200 equals 20400), but there are 9 legends that have a third finisher. 9 times 1200 equals 10800. 10800 plus 20400 equals 31200. So, it cost 31200 crafting Metals(Season 9).