Never played Multiplayer WazHack before? You can invite friends to play the same random dungeon, helping each other and sharing the experience, or competing to see who does best with the same resources.If you are playing at the same time, you can also see where other players are via an avatar icon. Note that you do not exist in each other's dungeon, but rather you are exploring the same dungeon independently - either competing to see who makes best use of what they find, or sharing knowledge and loot to make better progress.
First, set a Nickname in the Guild Hall. You will need to tell this to the people you want to play with.
Next, ensure that everyone who is playing is mutual guild friends with the person who will start the game. So for example if Adam will start the game, Betty and Charlie must be Adam's friend and Adam must be both Betty's friend and Charlie's friend. Betty and Charlie need not be friends with each other.
Next, one person starts a game from the Multiplayer menu. Shortly afterwards, the other player choose that game from their Multiplayer menu. They will then get to choose their class as normal before entering into the shared dungeon.
While playing, a network connection is established to show the avatars for all other players and to allow loot trading (only in co-op games). This is optional, you can turn it off by disconnecting in the Networking menu in the left-hand menu. The same menu can be used to reconnect if a player leaves and comes back. Players do not have to play at the same time at all, but it is a fun way to share the experience in "real time" (using a voice-chat program or being in the same room also adds to the fun!).