Cavern

The Cavern is a fifth level biome that was introduced with the Rise of the Giant DLC.

It is located beyond the Graveyard and served as a crystal mine for the King. It contains a variety of unique enemies in a series of carved tunnels, with a greenish visual atmosphere. The layout of the Cavern is particular, as it contains narrow shafts, probably used by the miners to move around the area, as well as floating platforms and pools of lava. The Cavern is initially the only way to reach the Giant, who is located in the Guardian's Haven.

Access and exit
The Cavern can be accessed from the Graveyard on all difficulties after defeating the Hand of the King at least once and having first accessed the area with the Cavern Key. Once the Giant has been defeated once, it can also be accessed from the Slumbering Sanctuary through a 2 BSC door.

The only exit out of the Cavern leads to the Guardian's Haven, where the Giant awaits.

Scrolls
The Cavern contains 6 scrolls, including 4 Power Scrolls and 2 dual-stat scrolls, which cannot spawn in areas requiring the Teleport, Ram or Spider runes. On (4+ BSC) there is a bonus Power scroll. When 3 Boss Stem Cells are active, this biome has 4 guaranteed Scroll Fragments, and when 4/5 Boss Stem Cells are active, this biome has 5 guaranteed Scroll Fragments.

Enemy tier and gear level scaling
In the table below, you will find the gear level and enemy tier of the Cavern based on difficulty.

Boss Stem Cells rewards

 * 1 BSC: Treasure chest.
 * 2 BSC: Treasure chest.
 * 3 BSC: Chained item altar.
 * 4 BSC: Festive Outfit.

Chests and loot

 * 1 treasure chest
 * 10% chance for a cursed chest.

Shops

 * 2 skill shops.
 * 1 weapon shop.

Secret areas

 * The blueprint for the War Javelin can be found in a secret area near the end of the level after a series of traps. In order to reach it, the player must use the Spider and Homunculus Runes.
 * The blueprint for the Festive Outfit can be found by unlocking a door with the Garland Key. The Garland Key is hidden throughout the level in a secret area on the roof, and while it can be found on any difficulty, the door itself can only be accessed on Nightmare/Hell mode, as it is located behind a 4 BSC door.

Enemy blueprints

 * The blueprint for the The Boy's Axe can be looted from Ground Shakers.
 * The blueprints for Magic Missiles and Shaman Outfit can be looted from Arbiters.
 * The blueprints for Ice Armor and the Flying Alcoholic Outfit can be looted from Skeletons.

Enemies
The Cavern is home to a few unique enemies, including Ground Shakers and Demons, in addition to more common ones. On higher difficulties, Lacerators are replaced by Failed Experiments.

In the table below, you will find which enemies are present in the Cavern depending on difficulty level. For each enemy, any common, uncommon, rare or legendary blueprints they carry are indicated. When applicable, the minimum difficulty level for blueprint acquisition is specified in brackets.

Alchemist grimoires
A research grimoire can be found next to barrels of crystals and a vat containing a body. The Alchemist was apparently trying to use the crystals as the ingredient for a cure for the Malaise.


 * "We can do more with those crystals than sell them, I'm sure of that... Using them on corpses doesn't do anything for now, but I have to keep going!"

King statues
A statue of the King can be found in the Cavern, next to barrels of crystals. The Beheaded notes how inflated the King's ego appears, that he would go so far as to bring statues all the way to the Cavern.


 * "Seriously? The King left one of his statues here? Is there no end to his ego?"

Other lore rooms
A lore room full of crystal barrels under the King's banner contains a letter left by a miner. It illustrates how isolated the miners were from the rest of the island's population, and how little they knew about the raging epidemic or the King's terrible measures to stop the spread of the Malaise. Despite being uninformed about the events outside of the Cavern, the miners were hiding weapons, which indicates they had met some monsters in their daily work routine and that the infection was reaching them.


 * "There are two kinds of people in the world: those with loaded crossbows and those that dig. ...We dig. We've dug for 7 months. 7 months here and still no news of the outside. I hope everything is fine."

A storage room full of crystals and banners of the King contains a letter left by a watchman, which alludes to the Giant. The letter states that the Giant, who previously guarded the Castle gates, has been slain due to an unknown feud between the King and him.


 * "The giant who was watching the castle gates is no more. What happened between him and the King, I wonder? ...I don't know what the Giant did, but judging by the spear, they must've had quite the... difference of opinion."

Trivia

 * This biome was added with update v1.2, also known as the Rise of the Giant DLC, released on March 28th, 2019.
 * Assets for the Cavern were already present in the game files in early access, long before the biome was officially added.
 * Occasionally, the Clock Tower can be visible far in the background of the level, beyond the Cavern itself.