Got mine from the world boss on the moon. That guy has insane health. You'll need a 6 man team. Here's how you get him to spawn: Get a group of 6 and start Crota's End raid. Don't jump down into the Hellmouth. Turn around and run to the Anchor of Light area. There's a red beacon on top of the central tower thingy. Get up to it and melee it until it stops blinking. Drancor, the unearthed will spawn in the area where the devil walker public event occurs. He takes a lot of firepower and every few seconds he'll send out a blast similar to Urrox's special attack but this one can't be avoided by jumping. Once he's dead you'll get a chance at any one of the exotics in the game. You can only do this once per week, per account.