Isntead of glimmer -> Strange Coins or Motes (or all three of them together). Notice that most people will only be activating this right before the exotic chest in VOG. 5min is plenty for that. alternatively make it a 1 week duration item that gets boosted by XP. ie: the more xp you gain the higher the possibility of it generating the item you want. While active it "sucks" all xp gains and you can deactivate it whenever you want. You wont be able to level anything up, no armour, no weapons, no skills, no motes of light, no REP, until you turn it off. Put it as a Ghost Shell -> Exotic Heavy Weapon Finder Shell, Exotic Primary, Legendary Primary , etc. Let Xur sell one type randomly like the engrams. You can buy as many as you want but only the last one remains active and you never know which one you will get until you pay for it. This would make people play more to "charge" the shell so that they can start harvesting their stuff. If at around 100k xp it gives you a 25% chance of getting what you want it would be excellent. Of course it will only give stuff from places where it can be obtained.