The mechanics of Dungeon Defenders 2 are designed around the genre of an Action Tower Defense, similar to it's previous entries: Dungeon Defenders and Dungeon Defenders Eternity. The Player controls a Hero who uses Abilities and Defenses to protect Main Objectives and Sub Objectives from hordes of Enemies summoned by the Old Ones.
A Hero is one of the Defenders of Eternia who is controlled by the Player. There are 13 playable Heroes. Players can have multiple versions of the same Hero. Players can create a new hero by pressing "ESC" and then selecting "Create Hero", or by opening their inventory with "I" and then selecting "Create Hero".
The Hero Deck is a system introduced in Dungeon Defenders 2. The Hero deck soft-limits the number of Heroes a Player may bring into a combat phase to 4 and these can be hot swapped between using the function keys. In the Build Phase defenders can access all of their Heroes. The Combat Phase has a small timer on Hero Swapping.
All heroes in your active deck during the combat phase receive the experience for that wave.
There are currently 2 Different Hubs in the game, the Private Tavern and the Heroes Market Place also known as Town. A Player may interact with the War Table in a Tavern or Town to gain access to the menu to start a Map.
The Hubs also have various NPCs from which you can buy items, transfer M.O.D.S., get costumes and much more.
Maps are where the majority of game play happens in Dungeon Defenders 2. Each map is an area in which players defend specific Main Objectives and Sub Objectives from waves of Enemies. There are currently 27 maps in Dungeon Defenders 2. Maps are started from the War Table in a Hub.
There are several types of accomplishments you can earn during the course of a match. For example, Feats are something earned for a particular wave of a match. Titles are something unlocked from a match that remain permanently.