The Iron sharpens Iron seasonal challenge is impossible for me to complete because Iron banner was only available twice for the entire season. In my case I missed the first iron banner week due to being on vacation. And for the second Iron banner week I simply did not play enough matches. Because of this 1 seasonal challenge I wont be able to get my large pile of bright dust and there's absolutely nothing I can do about it.
-
You don’t need all challenges for the bright dust reward.