Lets make it cost 250 coins, 25k glimmer, and it only buys you a common rocket launcher, which you level up by having to get the killing blow on Atheon, and Crota. Hard mode. You must then dance for a consecutive four hours. This has a chance to spawn a stealth vandal whose name is Panhandle. You must shake hands with him. All four hands, and it must be in order. (It is random.) He will then give you a uncommon rocket launcher that is called the Jellynator 6000. What do you do with the Jellynator 6000? Make a sammich, any kind. Eat it. Then go to Windurst and talk to some midget who has nothing to do with this mission. Why is it required? Well, if you don't do this you won't be able to get a cutscene to keep the story rolling. Why it's not in the quest log, I do not know. BUT once this is done, you go to Saturn and take a portal. This will warp you to the world of Diablo II. Use the Jellynator to land a killing blow on Diablo. He will drop an unidentified item. DO NOT TAKE THIS TO THE CRYPTARCH. If you do, you'll get a lime and lemon shader with a sign that says "Kick ME" on the back. Instead take it to Cain, who will identify it as a Blue rocket launcher. Complete all the strikes, be sure to kill the bosses with the rocket launcher. The last kill will drop you a legendary rocket launcher. Now level all the rocket launchers you have collected on this quest to max, which will reveal a hidden option with Xur to trade them in for an exotic heavy wep engram. Take it to the Cryptarch.