Okay, so heres my suggestion. I think that challenge mode is a great idea! It rewards us for doing things as it was designed or even a more specific and difficult way. However, ive completed the challenge modes since day 1 on all 3 guys and have an abundance of 320 artifacts as im assuming do a number of people My suggestion is that you should be able to "sacrifice" or trade in or buy a different item at 320 with the ones you have. Let me elaborate: If I provide lets say 10-20 320 Artifacts. I should be able to acquire a 320 class item or ghost. This sets a goal for doing challenge modes, meaning you'd need to do 3 a week for 6-7 weeks, and at the end of that time you would be guaranteed through sacrifice to receive the missing item that you've been searching for. It still extends game play, and would almost be closer to a quest than a vendor. Just my thoughts id love input and to potentially see it in the next update