Hey all, i’m a returning player (started on xbone and now on PC) and had a real quick question. I know that you need to transmute the Puzzle Ring in Kanai’s Cube to get to Greed’s Vault. I was working on my Act V bounty with my Necromancer and a saw a Gem Hoarder. So I corpse lanced it while it had the portal to greed open. I don’t know if I clicked on the portal or what but all of a sudden I was in the vault. Is this a bug or is this supposed to happen?
Thanks everyone.
The Greed vault portal was added a few years back, playing to the original lore entry.
The peasantry seem to believe that the goblins serve a great demon lord known as Greed, and furthermore, that their portals lead to Greed’s domain! A ludicrous notion, truly.
It’s 100% intended and random. Now, goblins can also open portals to the Cow Level upon death. And if you cube an Ancient/Primal Puzzle Ring, you’ll get a Vault full of goblins.
It’s a random occurrence, around 1-2% chance when a goblin dies. It could also spawn a portal to the not the cow level too.
Lastly, as an aside, if you use an ancient or primal puzzle ring you get access to the ancient vault with a LOT more rewards!
This is normal. Once you reach LV 70, all non-Rainbow goblins can spawn either a portal to The Vault or the Not the Cow Level (this is new to this patch!).
Awesome! Thank you everyone. Thanks for the additional information aswell! 
Don’t thank me yet, wait till you get my bill.
The puzzle ring and Bovine Bardiche do not have to be ancient. Take any puzzle ring to the cube and cube it. A portal to the vault will open. Likewise, take any Bovine Bardiche to the cube and cube it. A portal to the “Not Cow Level” will open. Both are good sources of materials and gold with the higher the T level the greater the reward. You also normally get a good amount of normal jewels from the vault.