Where and when can Treasure Goblin rifts appear?

Solution 1:

According to this green post, you should only be level 70 and be in Adventure mode.

Quote:

Goblin Realm:

• Spawns from random Treasure Goblins at level 70 in Adventure mode
• Only players present when the rift spawned can enter it

Please note, that only goblins found outside of the Rift will have a chance to open a portal.

Solution 2:

I have made it into several of these all from the same place. From what I can tell, it does not spawn inside of rifts nor in campaign mode.

The best place to find a goblin who will spawn the portal is in the Halls of Agony level 2. Take the waypoint there in adventure mode on any difficulty (difficulty affects gold drops), find the goblin, and cross your fingers. I have found the drop rate to be roughly 1 out of every 50 attempts.

Gold rates observed from the rifts (these rates include a bonus +100% from a community event).

• Hard: 4m
• Torment 1: 25m
• Torment 3: 37m
• Torment 4: 45m