During multiplayer, each player takes control of one of the two main heroes in both combat and NPC interaction. You are able to speak with each other and trade items with ease. Multiplayer is very similar to Single Player in functionality, but with a few key differences.
Local Multiplayer
Playing in Local Multiplayer is easy. Open the Game Menu at any time on a second controller and select your profile to join the current game. If you join during Character Creation, the second player will be able to customize their character.
Online Multiplayer
To host an online game you need to setup your Connectivity Options. You can do so in the Connectivity Menu, which is in the Game Menu. Multiple Options are available :
Open to everyone : Every player may freely join your game.
Open to friends : Only players in your friends list may freely join your game.
Invite Only : Only players you have invited may join your game. To Invite, select the empty slot below the options. You will then be asked to invite a player.
Closed : Nobody can join, the game is singleplayer.
To join a multiplayer game, select Join in the Main Menu. You will be able to setup multiple filters like the level of the party you wish to join. Once done, a list of the games that fit the criteria you selected will appear. Select one to join it.