The Dungeon is an enormous structure found close to the edge of the world opposite of the Jungle, spanning many layers deep, usually all the way to The Underworld. At world creation, the Dungeon is randomly formed from one of three Dungeon Bricks and walls (Can come in blue, green, or pink variants). It is the home of the third boss, Skeletron, who will guard the dungeon from characters that try to enter without first fighting him. Upon gaining access, the player can roam about fighting deadly enemies, dodge numerous traps, discover powerful loot, and free three different NPCs: the Mechanic, the Goblin Tinkerer, and the Wizard.
The dungeon is made up of Dungeon Brick. It requires Nightmare Pickaxe/Deathbringer Pickaxe or higher to mine and is immune to explosives. The dungeon zig-zags down from the entrance to a larger, labyrinth like section where the majority of the loot can be found. The winding nature works to make monster spawns unpredictable, creating many "ambushes" from above. It is highly recommended that every character have a Magic Mirror for quick escape, as getting out is often more difficult than getting in as a result of needing to go up.
There are many rooms branching from the labyrinth where a great deal of loot can be found and can be a good resting place as monster only have one access point to the character.
Spikes line much of the dungeon making simple traversing dangerous. They can be mined, but are harder than the dungeon brick. Placing blocks or platforms over them is recommended.
Three different NPCs can be found anywhere within the dungeon, and will be bound until you right click on them and untie them. The Mechanic NPC will most likely be the first one you find, because it has no spawning requirements, unlike the other two. The Goblin Tinkerer can be found in the dungeon once you have defeated your first Goblin Army. The last NPC you can find is the Wizard, which can only be found once the Wall of Flesh has been defeated and Hard Mode is activated.
The dungeon has a large number of unique monsters. The monster spawn may be abnormally high as there are Water Candles spread throughout, so try to break them while traversing the dungeon to keep the rate down.
To gain access to the Dungeon, Skeletron must first be defeated. Skeletron is the guardian boss summoned by talking to the Old Man standing outside the Dungeon entrance at night. During the day, he will say to wait until night to talk to him. Entering the Dungeon below 0 Depth without first defeating Skeletron will cause the Dungeon Guardian to spawn, which can kill a player on contact.
The Dungeon is filled with chests containing rare and powerful tools and weapons as well as unique decorative items. Loot in the dungeon can be found laying around, as drops from monsters, or in chests. All Gold Chests found in the Dungeon are locked and require a Golden Key to unlock them. There are also 5 Hardmode Chests, described below.
Gold Chests may contain, along with normal chest loot:
- Aqua Scepter
- Blue Moon
- Cobalt Shield
- Golden Key
- Magic Mirror
- Magic Missile
- Shadow Key
Other loot from the dungeon includes the Water Bolt spell, which can be obtained by smashing books in the dungeon. Dungeons are also a free source of wire and many wiring items. There are also many decorative furniture items, including paintings, beds, chairs, and workbenches, that can be found throughout the dungeon.
Once Hardmode has been activated and Plantera has been defeated, the Dungeon becomes much more difficult. New types of enemies will spawn. When these new enemies are killed there is a chance to spawn a Dungeon Spirit, which will drop Ectoplasm used to craft Spectre items. You can easily farm the drops from these new enemies, as well as Ectoplasm. Here is a video to help explain how you can farm the mobs.
Along with new enemies, the five special locked chests will become accessible (the keys to these chests will only drop in Hardmode). They each require a matching key. These keys can be obtained by killing enemies in the corresponding Biomes to get the Key Molds, and then craft with various items (the enemies do not have to be native to that biome). The drop rate is 0.04% or 1 in 2500, making them very rare. Either the Corruption or Crimson chest will not be unlockable, depending on if that world is infected with The Corruption or The Crimson, unless the player goes to a world that has the other infection.
- It is possible to make a Home in the Dungeon by taking out the background walls, placing different walls there, and putting down a bed. This will allow a character to spawn there, and it prevents monsters from spawning.
- The bottom of the Dungeon will sometimes cut into the Underworld, providing a viable way to access The Underworld. This can happen on any world size, but it is more common on smaller worlds.
- In Hardmode it is possible to hear underground Hallow/Corruption instead of the normal dungeon theme if Hallow/Corruption is nearby and also for dungeon monsters to drop Souls of Light/Night.
- If the bottom of the Dungeon reaches the Underworld, the Corruption/Hallow can't spread past the Dungeon as it separates the surface world. If the Dungeon doesn't go that deep, it'll still take the Corruption/Hallow very long to spread past it, going all the way around.
- Sometimes, a boulder trap will spawn in the ceiling of a dungeon. This could be an easy way to get inside the dungeon without going from the entrance.
- Occasionally, parts of the dungeon will be flooded.
- Loot is spread evenly throughout the Dungeon, so loot further down is not necessarily better. Sometimes when exploring the dungeon Skeletron may reappear and attempt to fight the player, but restarting the game should fix this.
- Mining close to the Dungeon without defeating Skeletron will cause Dungeon Guardian to spawn and target the player.
- The dungeon is always on the opposite side of the world from the Jungle.
- 5 new kinds of locked chests added to the dungeon: Corruption Chest, Crimson Chest, Jungle Chest, Hallowed Chest, Frozen Chest
- The dungeon now spawns new enemies in Hardmode.
- Added Furniture, Banners and new Light Sources.
- Dungeons are now generated with traps and light sources wired to pressure plates or switches.
- Dungeon can now be flooded.
- The bug where the Ocean overlaps with the Dungeon at world creation time has been fixed.
- Gold Chests are now locked and must be opened with a Golden Key.
- Dungeon Slime, Blazing Wheel and Spike Ball enemies introduced.
- The ability to construct artificial dungeons has been removed, any placed dungeon background walls will automatically be considered as Home Tiles.
- Entering the Dungeon without defeating Skeletron now spawns the Dungeon Guardian rather than Skeletron's head.