The Dungeon

Ramiris' Labyrinth was created using Ramiris' Intrinsic Skill, Labyrinth Creation. The labyrinth is a part of Tempest as well as Ramiris’ territory. When Rimuru gave Ramiris permission to establish the labyrinth, he also granted her extraterritorial rights on that place. The inside of the labyrinth is under both Rimuru's and Ramiris' control, established as a special area under the administration of joint sovereignty. Veldora is the final boss of the labyrinth and rules over the dungeon while Ramiris supervises it.

Features
The labyrinth was created via a number of blocks, allowing the layout to be changed every few days. The environment in the labyrinth is fully under Ramiris' control -- the sky is visible in certain floors, and it is even possible to make it rain.

While in the labyrinth, Veldora constantly flaunts his aura in the 100th floor. Once the magicule concentration increases, monsters will naturally spawn. As it trickles upwards, the upper floors are occupied by small fry with strong beings further in.

The entry fee of the labyrinth is three silver coins. Several exclusive magical items crafted by Ramiris are sold at the entrance to aid the challengers' quest:


 * Resurrection Bracelet: By wearing the bracelet, any death that occurs in the labyrinth will be negated, and the user will be returned to the surface with all wounds healed. It will nullify the pain of fatal wounds and activate ten seconds after death has been confirmed, allowing other party members to revive the fallen. It's given for free for the first time, and costs two silver coins for subsequent purchases.
 * Return Whistle: Single-use item that return the user to the outside instantly. In essence, it was an item made for emergency usage. It costs 30 silver coins each and is limited to single-person usage.
 * Recording Crystal: Allows the user to create a one-time save point and return to the recorded spot during their next entry. It costs one gold coin each.

Treasure chests could also be found within the labyrinth, some of which guarded by monsters. There's a chance to obtain potions, items, coins or prototype equipment made in Kurobe's workshop. There are three type of treasure chests in ascending rarity and quality: bronze, silver and gold. Bronze chests could be traps or mimics, whereas it is possible to obtain Rare or Unique grade equipment in silver and gold chests, with gold chests having higher chances.

By having newly born monsters swallow items and equipment, it became possible to get item drops from monsters. This incentivized the challengers to hunt more monsters, which also helped in supplying more magic crystals and monster parts in the market.

Notable Floors
Initially, a safe zone was created every 10 floors. There is a Boss room before each, and they can only access it after defeating the boss. There, they will be able to purchase magic stones, sell drops, and buy potions at very high prices. In Volume 10, the safe zone system was removed, and had since been replaced by a door leading to shops and accommodation facilities on the 95th floor.

1
The first floor is a square-shaped room spanning 250m on each side. It is intended to have the challengers familiarize themselves with the labyrinth, therefore there's nothing much hindering their progress other than its sheer size. It was converted into a tutorial/training area in Volume 10 to provide basic guidance, as it's obvious that most people aren't familiar with dungeon exploration.

2
This is where the dungeon really begins. There are no deadly traps and the monsters appearing are of merely F ranked small fry.

51-60
These floors are filled with traps made of scientific weapons like laser beams, sonic cannons, poisonous gas, and large numbers of golems.

61-70
Undead monsters under Adalman's command occupy these floors.

71-80
These floors are occupied by giant insects, including deadly Legion Bees under Apito's command.

81-90
These floors are paradise for magic beasts. From the 82nd floor onwards, each floor is guarded by one of Kumara's tailed beasts.

91-94
These floors serve as production and storage facilities.


 * 91st floor: storage facilities for metal ores.
 * 92nd floor: magisteel production plant.
 * 93rd floor: a farm to cultivate Hipokute herbs for potions.
 * 94th floor: garden and honey production facilities.

95
The 95th floor was established as the residence of the treants and elves, thus it became a floor of overgrown greeneries. This dome-shaped floor has the widest area, spanning the diameter of 5km. Around the door that leads to the 96th floor is the last save point before the final boss. Many important facilities are housed in this floor, including:


 * Adventurer's Inn: Offers food, accommodation, baths and laundry services for prices higher than on the surface.
 * Equipment Shop: Offers special weapons and armors in their storefront, which can only be found and purchased here. Adventurers could also pay to repair their gear.
 * Elf Cabaret: One that's similar to Night Butterflies in the Armed Nation of Dwargon. Only important members with a VIP pass may access this facility.
 * Research Facility: A joint research facility for elves, dwarves, humans and vampires. The Magic Train was developed here.

There's a door that leads to the 95th floor besides the stairs on each floor, with the entry fee being three silver coins. Those visiting through the door could only access the inn and equipment shop, however. Only those who legitimately reached cleared the 90th floor could have free access to all facilities.

Dragon/Terrain Floors
The dragon/terrain floors were arranged in order of strength, fire>ice>wind>earth. The dragons feed on magicules released by Veldora's, hence they can live there without issue. The tamed dragons were assigned as Ramiris’ subordinates.

96
The 96th floor is the Floor of Tremor -- as to ridicule the one that managed to come this far, a fiendish earthquake will befall them. This floor is guarded by Earth Dragon King Euros.

97
The 97th floor is the Floor of Storm, with the threat of lightning striking from the sky. Whether one can break through this floor or not depend on one's luck. This floor is guarded by Wind Dragon King Notos.

98
The 98th floor is the Floor of Blizzard Hell. If one stops, they could die; one might be able to make it through with cold-resistant equipment. This floor is guarded by Ice Dragon King Boreas.

99
The 99th floor is the Floor of Inferno, the gateway towards the final boss covered in scorching flame. Heat-resistant equipment is needed. This floor is guarded by Fire Dragon King Zephyrus.

100
On the 100th floor lies an entrance leading to the spirits’ labyrinth, and Veldora is the strongest guardian to protect this gate. Veldora's chamber is a square 100m wide on each side, and was created in a way that it can be expanded if it's ever necessary. Other than Veldora's Chamber, there are several other facilities, namely:

Veldora's Private Room
A room for Veldora to relax in his human form. It is fully furnished, including a bed. Veldora usually reads his manga in this room.

Rimuru's Private Lab
The place where Rimuru runs his passion projects. He prepared the 1000 homunculi bodies for the demons recruited by Diablo here.

Ramiris' Private Lab
This is where Ramiris runs her research projects. She was later joined by Dino, and subsequently Shinji Tanimura, Mark Lauren and Zhen.

Strategic Military Control Battle Command Center
Commonly known as the "Control Room". This room houses the displays of Physical Magic "Argos" for surveillance, and is the place where military strategy meetings were held. It's possible to directly access other important facilities housed in the labyrinth from here.

Floor Guardians
As the challenger reaches floors numbered in multiples of 10 and the last 5 floors, they will encounter a floor guardian that are much stronger than usual monsters. The most prominent among them are the Ten Lords of the Labyrinth, dwelling in the lower floors.

Save points are available every 10 floors after defeating the respective floor bosses. Upon reaching these points, one can continue from where they left off the next time they entered. To that end, licenses to use magic teleportation circles are granted to adventurers.

Upper Floor Guardians:


 * Guardian of the 10th floor, Black Spider, Rank B
 * Guardian of the 20th floor, Evil Centipede, Rank B+
 * Guardian of the 30th floor, Crazed Ogre, Rank B+, as well as 5 of its rank B subordinates
 * Guardian of the 40th floor, Tempest Serpent, Rank A-
 * Guardian of the 50th floor, Gozurl, and Mezurl

Lower Floor Guardians:


 * Guardian of the 60th floor, Gadra with the Demon Lord Protector Colossus
 * Guardian of the 70th floor, Immortal King Adalman
 * Vanguard of the 70th floor, Death Paladin Albert
 * Tank of the 70th floor, Death Dragon
 * Guardian of the 79th floor, Insect Queen Apito
 * Guardian of the 80th floor, Insect Kaiser Zegion
 * Guardian of the 90th floor, Nine Head Kumara
 * Guardian of the 96th floor, Tremor Dragon Lord
 * Guardian of the 97th floor, Storm Dragon Lord
 * Guardian of the 98th floor, Frost Dragon Lord
 * Guardian of the 99th floor, Inferno Dragon Lord

Traps

 * Poison Arrows: Arrows smeared with poison come flying out of nowhere.
 * Poison Swamp: A swamp that is really poisonous. If one falls into one, they'll get poison damage and abnormal status.
 * Turning Tile: Drive one's sense of direction mad.
 * Moving Tile: A floor that moves all by its own.
 * Cutting Thread: If one passes by it without realizing, one's head will come off. Combined with moving tile for brutal results.
 * Pitfall: Rather than the damage dealt by falling down, what's awaiting one when they fall is scarier.
 * False Treasure Box (Mimic): A false treasure box that is actually a monster.
 * Monster Room
 * Sealing Room
 * Darkness Floor
 * Low Ceiling Floor
 * Terrain Effect Floor
 * Airtight Room: If one suddenly enters into a room without air, they'll fall from not being able to breathe, at worst die. It is recommended for one to use wind magic for ventilation.

Trivia

 * Hinata Sakaguchi is the only challenger who reached the 100th Floor and fought Veldora. It happened before the Ten Lords of the Labyrinth was established, however.
 * Since all monsters in the labyrinth are spawned from Veldora's magicules, all of them can be considered as Rimuru's siblings in a way.