I have 13/14 complete. the only thing left is the season of the undying badge.
Hey there, You will need to complete the Undying Badge for the final triumph. You can find your badges on the same page as your collections, in the bottom right corner.
That item is asking you to collect all the items on the Undying Badge. You can view the Undying Badge by going to your Collections and the badges are on the right-hand side. The Undying Badge should be the last item in the list. Inspect it and it will show all the items from Undying you need to collect to complete that badge.