With patch 2.1 a new instance called “The Vault” has been added which can spawn when a treasure goblin is killed. Inside this instance are many treasure goblins with a boss goblin at the end called “Greed”.
Once you get the spawn, equip as much gold find gear that you can handle while still being able to kill the goblins. Clear through the area, you will eventually make it to Greeds level. During this boss fight Treasure Goblins will spawn every time Greed uses her charge ability. Do not finish killing the boss until all the treasure goblins have spawned, there is a set amount just wait until a charge doesn’t trigger another goblin spawn.
After defeating Boss Greed a chest will spawn some random legendary items and a legendary gem called Boon of the Hoarder, which is guaranteed to drop on first kill. This gem gives you a chance to spawn gold when killing enemies which you can rank up the higher via Greater Rifts.
Use this gem in future Vault runs or other areas of the game that have a high mob density.
Oh yea