The Dungeon is a POI in Zone 2 of Road To Eden where can be found the Reactive Armor Block recipe, special Weapons (Enforcer, Bright, Ice Razor, Liberator, Arabian, Forbidden Glory, Punisher), and rare Ores (Crocoite Crystal, Atacamite, Chalcopyrite Crystal, Kyanite Crystal, Quartz Crystal, Dioptase Crystal, Citrine Crystal, Granite).
The Dungeon is located in J-2. It is infected with Petrified skeletons, Infected, Spitters, Thumpies, Small and giant spiders and Protopods.
In order to open the entrance door, you need to craft a Dungeon Key Level 1.
Some parts are still to be explored but the core locations are there :