Press [E] to enter an Uber-6 Adventure World. Complete dungeons in this world for Moon Key Fragments.
The Prime World Adventure Portals are four portals built for players with 1,200 Power Rank and above. These Prime World Adventure Portal can be accessed from the Hub, Club World or cornerstone.
Defeating bosses and lair/dungeon objectives will reward moon key fragments.
All of the Prime World Adventure Portals lead to worlds with all of the biomes.