His available items for purchase are different every week as well. You’ll have to save your Strange Coins during the week and visit him in the weekend in order to purchase the Exotic loot he has for sale. Xûr only shows up in the Tower on the weekends, from early Friday morning (9am GMT) to early Sunday morning (also 9am GMT.) In Destiny, Strange Coins are a form of currency that you can use to trade with Xûr, Agent of the Nine when he is in the Tower.
