While there are many means of classifying dungeons, perhaps the most common and useful is by monster type. While there is no known limit on the number of types a dungeon can adopt and use over the course of its life, some types appear to be mutually exclusive, here organized into pairs, while others appear only to be available to a dungeon which has already chosen its first type, and so we will focus only on those "basic types" in this chapter.

There are sixteen known basic monster types, each of which has its own strengths and weaknesses to consider. Whichever basic monster type serves as a dungeon's "first monster" will shape the dungeon's every action going forward- while a beast type dungeon summoning a humanoid monster might summon powerful werewolves, a humanoid dungeon summoning a beast type monster would summon wolf-riders, dangerous high speed monsters capable of attacking as both a wolf and rider. While each dungeon can only have one primary type, and all monsters in the dungeon will share that primary type, each monster can have a secondary type, and the variety of types available within one dungeon seems nearly unlimited. Virtually every monster type will convince some parties to stay away from a dungeon, if only due to a capability mismatch.

Beast dungeons use powerful but simple minded monsters to defeat enemies in direct combat, leaving little to chance, but providing opportunity for the wise to exploit weaknesses. Their initial monster, the Giant Rat, while powerful for its rank and numbers, is little threat to a canny adventurer. Despite this, they can be terrifying for beginners, as those who have not learned how to spot the signs of more advanced versions, such as Plague Rats or Ripper Rats, can be taken entirley by surprise when they ignore the flame and either rip a party apart or infect a member with a lethal, if mercifully non-infectious, disease. For this reason, as in any dungeon, caution is paramount.

Undead dungeons use simple minded automata, not entirely unlike those used in mechanical dungeons. While these undead are individually no threat, they come in large numbers and will complete their orders, even if it means their destruction. Canny dungeons have been known to wipe entire raiding parties by simply having a chamber which serves as a skeleton crypt rigged to collapse, and simply ordering a skeleton to trigger the trap when the party is dedicated to the fight. Perhaps their most infamous trait, however, is their basic monster's capability for revival- when leaving an undead dungeon, one should always take great care, especially when passing through a former battleground.

Magic dungeons use a wide variety of monsters, from the simple and almost inoffensive slime, to dangerous and frightening enchanted swords and spears. Magic dungeons are also well known for rapidly branching out, forming dual type monsters much faster and more frequently than other dungeons, allowing them access to powerful golems, magically gifted shamans, and dangerous cross-bred beasts. Their basic monster, the slime, is almost no threat, but marks a clear warning for any unlucky intruders of what lies ahead. While they start off relatively easy to deal with, an ancient magic dungeon can be one of the most dangerous to delve.

Mechanical dungeons rely on complex clockwork mechanisms, automata, and monsters which maintain them. Notable first and foremost for the sheer number of traps within their dungeons, and the frequency with which they can reload, these dungeons also have the dubious honour of being the dungeons known to have the most complex and subtle triggers, meaning even after a trap goes off, you may have no idea what triggered it. Unlike skeletons, mechanical automata are costly, high tier monsters, and so they are rarely used as disposable trap triggers. Mechanical dungeons are also notable for almost always taking Humanoid as their second type, in order to unlock monsters such as gremlins. Their basic monster, Clockwork Spyders, are no threat in combat, but remain one of the most hate elements of these dungeons for a simple reason- they have the ability to reset traps while invaders are still in the dungeon, sometimes even while in the same room as them, thanks to their small size.

Fire dungeons rely on heat and burns to defeat their enemies. Early in their lifecycle, they are often little threat, as their basic monster, Lesser Salamander, moves slowly when in temperatures a human can withstand. However, as a fire dungeon matures, the ambient temperature in even the first floor rises, rapidly requiring magical assistance to even enter the dungeon, which in turn allows the lesser salamanders to reveal themselves to be a threat on par with Giant Rats, but without any fears to exploit. Luckily, lesser salamanders can only spit flame once per day, or they would likely be able to maintain a high temperature within the dungeon all on their own.

Aquatic dungeons are perhaps the most hated and loved of dungeons, as those who explore them swear by their unique style and dangerous beauty, but everyone else recognizes that without specifically setting out to learn underwater combat, these dungeons are death traps. Do not, under any circumstances, enter an Aquatic type dungeon without training in atleast one style of underwater combat and atleast two means of breathing underwater. Their basic minions, Giant Crabs, can fight equally well on land or in the water, but prefer to dwell in the deep pools invaders are often forced to swim through, allowing them to pick off their enemies from below while they are helpless and, preferably, unaware.

Humanoid dungeons have perhaps the greatest variety of monsters, having many paths they can go down in their first floors before even selecting a second type. Well known for their intelligent minions and fortifications that force attackers into disadvantegous positions, these dungeons require sound tactical thinking and a helping of overwhelming force to overcome. Their basic monster, goblins, are cowardly and easily scattered, but become much more dangerous when competently led. For this reason, targeting the leaders is generally the accepted method of defeating goblin fortresses, as once their leadership is gone, they will often scatter.

Stealth dungeons contain a multitude of ambush predators, and rarely grant even a moment's reprieve. Some have even been known to hide monsters within the stairwells between levels! Those wishing to explore these dangerous dungeons are advised to bring a multitude of antidotes, as venomous creatures are common throughout the dungeon. Their basic monster, the viper, provides perhaps the most representative example of what a dungeon will do, hiding in wait before striking, and often disabling a party member before it can be put down. Luckily, young stealth dungeons contain numerous holes in the walls, floors, and ceilings for monsters to hide in, which also serves as an immediate warning of what type of dungeon a party is entering.

Plant dungeons blur the line between monster and trap, summoning powerful ents, entangling thorns bushes, spitting vines, and subtle pitcher plants. It can be difficult to tell where a threat is when in a plant dungeon, but once spotted, they are often trivially easy to avoid, with rare exceptions capable of unassisted locomotion best lured away from their home. While their basic monster, spitter vines, are barely more dangerous than the common arrow trap, they are notable for one interaction- spitter vines can wind around any tree, including ents. This grants the ent a ranged attack, and the spitter vine the ability to chase after enemies.

Rock dungeons present a unique challenge to smiths, not to adventurers, as their monsters bare rocky skins and dense flesh, require exquisitely crafted, powerful blades in order to successfully defeat them. More importantly, many rock dungeon monsters are composed of rare ores, which can be used to craft even more powerful blades. In regions with no access to rock dungeons, the first to appear can be a godsend, but equally a nightmare, as the lack of exceptional ores can make the retrieval of these same ores from the dungeon next to impossible. In such circumstances, warhammers and maces are advised, as they can somewhat overcome the difference in quality. Their basic monster, Gnome, is simply a small monster made of rock, slow moving, physically tough, and with dangerous attcks. Their fists are usually composed of high quality iron ore, and their eyes are cheap gems.

Bird dungeons favour wide, tall open spaces, often focusing on a single enormous room on the first few floors, before becoming powerful enough to create multiple rooms with passages both in the air and on the ground between them. While bird monsters on their own are typically easy to defeat, being relatively fragile, they are often exceptional at dodging attacks, and some have powerful ranged attacks which keep them from ever needing to approach the ground. Worse still, the large floors means an entire flock can gather and attack at once, leaving victims helpless. Their basic monster, Razor Hawk, is known to target victim's eyes, wrists, and necks, so protective cover of these areas is strongly advised.

Electric dungeons rely on unique traps and stunning shocks from fast moving monsters. Mercifully rare, these dungeons are come in two varieties- the foolish ones which behave as if they were any other dungeon, and the cunning, cruel ones which understand their unique advantage, and attack with hordes of weak monsters, hoping to permenantly disable invaders. Their basic monster, the Lightning Bug, is a perfect example of this, and discharges a shock capable of immobilizing anyone without appropriate resistances for a full second- which is all the opening the swarm needs. Like aquatic dungeons, absolutely do not enter this dungeon without appropriate preperation

Horror dungeons are unique, in that they do not kill their victims, instead turning them into new monsters. Due to this, they often overflow their own capacity to contain monsters, which you may recognize as the primary cause of Stampedes. Due to this, horror dungeons are carefully monitered, and if their subtypes and styles prove too dangerous, overwhelming force is used to destroy them.

Healing dungeons serve as a reprieve from the hostility of regular dungeons. These rare dungeons appear to come into being when a dungeon which has yet to summon monsters discovers the value of captives, and decides to focus around exactly that. Healing dungeons do not have a single basic minion, as the type seems to arrive so late they can immediately select a specialization. Once a healing dungeon comes to understand that it can barter with humans and other sapients, it is said to be fully mature, and will begin to disarm its own traps, in order to appear more peaceful. Unfortunately, this honest aim of cooperation and friendship seems to make them common targets for those seeking the power of a dungeon core, and most either die before establishing a third floor, or become the exclusive property of an organization powerful enough to protect it. The lone exception has an unknown number of floors, of which only the first five are actually devoted to healing, and it teaches a valuable lesson to adventurers- no matter how tame a dungeon may seem, it is still a dungeon. It can and will kill you if you threaten it.

In a later chapter we will discuss advanced types, as well as particularly notable combo types, but this should be enough for a broad overview. Perhaps the most important lesson for any new delvers to learn, however, is this: No two dungeons behave identically. Even if two dungeons have the exact same types, subtypes, and monsters, they may use those monsters in different ways, have different goals, prefer different kinds of adventurers, or, most crucially, give different loot.

-Gerald Ironhide, Dungeons for Delvers, A Novice Adventurer's Guide