Dungeons are a 3v1 encounter with a powerful enemy rewarding players with the chance to win common, uncommon, rare, epic and legendary characters and equipment.
Legendary characters & items can be looted in any dungeon, even the earliest dungeon "Brigand Base"
The first Dungeon unlocks when you have completed Level 10 of the Campaign, further dungeons unlock as you defeat each dungeon.
Victory in a dungeon will always reward you with loot. Standard loots are 250 blue gems, a character or a piece of hero equipment.

Deck Limitations

Some earlier dungeons have deck limitations to prevent experienced players from exploiting them for easy loot. These are indicated to the right of the start button as you enter a dungeon.