The vault will start to spawn when the goblin dies. You will see a little swirl animation and then the portal pops up. Anyone that was in the game at the time of the goblins death may enter the portal. You do not have to be near the kill either. You could be in town or in another location farming and someone could kill a goblin and spawn a portal then you could zone to him and enter. Anyone who enters the game after the portal has spawned can NOT enter, though they can see it in the world.
Grimiku: A very accurate description! To reiterate, the portal to the Vault can spawn in both solo and group setups in Adventure Mode (though not inside of Nephalem or Greater Rifts). In addition, any players who were in the game at the time the portal spawns are eligible to enter it, though they need not have been part of the goblin kill itself.
The Vault, Greed’s Domain: Q&A.
I’m sure there are some other common questions, but those are all the ones I can think of right now. If anyone has some more hit the comments and I’ll update the list.
Also, thanks to Mormith for the tip about getting a second Boon of the Hoarder, if you find The Vault with a character who already has one equipped. Here’s his email for the full context:
I listened to part one of the legendary gems podcast and was amused to hear of your love for “Boon of the Hoarder.” I had just spent two weeks killing 174 goblins to finally get one of my own. The very next day (yesterday) I was raking in the gold doing act 1 bounties for a RoRG when a second goblin portal opened! With none of my friends online to help keep the game open while I switched chars (to one without BotH), I eventually tried something risky that worked.
I unsocketed BotH, dropped it on the ground in town, portaled back to the where the goblin portal had opened (I hadn’t gone in yet) and quickly fought through to the end where I got another BotH as a reward. Portaled back to town where my original gem was still on the ground and now I have two— WooHoo!
Hope this isn’t old news to you, it might be of help to someone.
This should also work for any other Legendary Gem from a Greater Rift Guardian. You’d have to plan ahead though, and drop the gem before you even opened the Greater Rift, since once the portal is open you can’t access anything in your stash or inventory or equipment.
Of course the easier way is to just hold some Legendary Gems on another character. The game will drop at least one LGem with each dead GR Guardian, *if* any of the 13 LGems (not including Hoarder) is not presently in your stash, inventory, or the gear of the character you are playing. Many players have worked the system to get additional LGems so they can level them up for an alt, or save up/level up some extras in Hardcore, so the inevitable death won’t leave them without any of their favorite kind. LGems are fantastic twinks, adding tremendous damage and utility from socketed rings/amulets even on low or mid level characters. I was just doing it tonight and let me tell you… leveling up an alt with a Conduit Gem in their gear is amazingly fun. Boon of the Hoarder is awesome as well.