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 4 playable Heroes. Players can have multiple versions of the same Hero but are limited to 6 total characters on their account. To create a new Hero, a Player must be in the Social Tavern.
The Hero Deck is a system introduced in Dungeon Defenders 2. The Hero deck limits the number of Heroes a Player may bring into a match to 3. To change the Heroes currently in the Hero Deck a Player must be in either the Social Tavern or a Game Lobby Tavern.
The Tavern in Dungeon Defenders 2 serves as a Hub. There are 2 Different Taverns, the Social Tavern and the Game Lobby Tavern. The Social Tavern is where a Player appears when they enter the game. The Player cannot control which instance of the Social Tavern they enter in to. From the Social Tavern a Player may speak to the War Recruiter to enter into a number of different game queues based on level and difficulty. Once a player selects a queue and clicks on the "Find Group" or "Private Game" lobby they are transferred to the Game Lobby Tavern (Unless they queue into a "Find Group" with a game already in progress).
The Tavern has a number of NPCs that the player may interact with, including Shops, Lily's Upgrade Shop, and a daily quest giver as well as a Defender's Forge and Hero Manager. The only difference in interactables in the 2 taverns is the War Recruiter and the War Table.
Maps are where the majority of game play happens in Dungeon Defenders 2. Each map is a instanced area in which a player defends specific Main Objectives and Sub Objectives from waves of Enemies. There are currently 10 maps in Dungeon Defenders 2. Maps are started from the War Table in Game Lobby Tavern.
The Defender's Forge is an interactable station that is present on every map and in both taverns. The Defender's Forge serves as the place for a Player to manage their Inventory and Heroes, as well as look at their Collections and Achievements. The Forge can also be accessed anywhere by pressing "i" (default inventory key).
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.