TerrainSpecial Lair

A Mysterious Cave is one of the seven most basic Encounter Zone types. These are among the easier Encounters (relatively speaking), where the sites themselves have no added functionality. Mysterious Caves are guarded by Fantastic Creatures of the Icon Nature.pngNature Realm in the official game, and either Icon Nature.pngNature or Icon Chaos.pngChaos in Insecticide or later. Depending on which Plane the Mysterious Cave appears on (i.e. Arcanus or Myrror), it may contain anything up to and including Icon Nature.pngGreat Wyrms (or Icon Chaos.pngGreat Drakes). Some Mysterious Caves are empty (containing no monsters).

The reward for defeating a Mysterious Cave's guardians is random, and varies based on the strength of these creatures. It can range from small amounts of Icon Gold.png Gold and Icon Mana.png Mana all the way up to new Spellbooks and Retorts (and, occasionally, "Absolutely nothing"). If the Treasure contains one or more Spellbooks, they will be books of of a random type (Wizards possessing any Icon Life.pngLife books cannot get Icon Death.pngDeath, and vice versa).

Unconquered Mysterious Caves may occasionally spawn Rampaging Monsters, a group of Neutral Fantastic Units matching the Realm of the site's defenders. The strength of these stacks increases as the game matures. These monsters will head straight for a nearby Town controlled by one of the Wizards. On the higher Difficulty Settings, they will typically target the human player's Cities.

Description Edit

A Mysterious Cave is the domicile of Fantastic Creatures, who will defend their homes ferociously if disturbed. However, these "monsters" are also known to hoard valuables that adventurers generally find rather appealing. For this reason, Mysterious Caves rarely remain unchallenged for long.

Mysterious Caves appear on the map as brown domes with a hole in their sides. They look identical to Monster Lairs, and also behave exactly the same in every way. The Surveyor (F1) can be used to discern which type of site the structure actually is (referred to simply as a "Cave" or a "Lair" by the tool).

As with other basic Encounter Zones, the Mysterious Cave can appear almost anywhere on the map, as long as it is on land type terrain (excluding the polar Tundra strips). The only restriction is that it may not be adjacent to another Encounter Zone.

The Encounter Zone Edit

Main article: Encounter Zone
Encounter Cave Dialog

An example Mysterious Cave scouting dialogue.

As long as they appear on the map, every Mysterious Cave designates an Encounter Zone. That is, a randomly generated group of neutral creatures defending some sort of Treasure. The value of this Treasure is inexorably tied to the strength of its guardians, i.e. the stronger the monsters, the better their Treasure (on average at least, considering that it is ultimately random). The following sections explain how the game chooses these creatures and the rewards for defeating them.

Normal/Weak Mysterious Caves

Before deciding anything though, each Mysterious Cave needs to be discreetly assigned a relative toughness out of two choices: it will be either "Weak" or "Normal". Weak Mysterious Caves are slightly more common on either Plane, as the game creates a total of 32 Weak "Lair" type Encounter Zones for each campaign, as opposed to only 25 Normal ones. However, Mysterious Caves are only one of 7 different "Lair" variants, and their exact amount and toughness will vary from game to game.

These choices are made randomly at the start of every campaign, and will determine the relative strength of the Mysterious Cave' defenders, as well as the value of the reward for defeating them.


Each Encounter Zone can contain up to 9 defending units. These are always Fantastic Creatures, and any single Mysterious Cave can feature up to two different types of them. However, they will always be of the same magical Realm.

The exact types and amounts of the guardians are determined through several steps, the first of which is setting out an "encounter budget", which defines the total possible value of the defending units. For a Mysterious Cave, this is determined randomly using the formulae listed below. The budget ranges are different based on the game version being used, as the unofficial patches gradually increase it:

Mysterious Cave Creature Budgets
Zone Type v1.31 Formula v1.40 Formula v1.50 Formula
Weak Mysterious Cave Arcanus Random(10) × 10
(10 - 100)
Random(10) × 30
(30 - 300)
Random(20) × 30
(30 - 600)
Myrror Random(20) × 10
(10 - 200)
Random(20) × 30
(30 - 600)
Random(30) × 30
(30 - 900)
Normal Mysterious Cave Arcanus Random(29) × 50 + 50
(100 - 1,500)
Random(29) × 50 + 250
(250 - 1,700)
Random(80) × 50 + 250
(300 - 4,250)
Myrror Random(24) × 100 + 100
(200 - 2,500)
Random(24) × 100 + 250
(350 - 2,650)
Random(90) × 50 + 250
(300 - 4,750)

This base budget is then adjusted for the campaign's Difficulty Setting, in +/- 25% increments (using "Hard" as the baseline), depending on the game version. The "Intro" Setting is only available in the official game, and is replaced by an "Extreme" Setting (which is in a different location on the Difficulty scale) in Insecticide and later.

Version Intro Easy Average Hard Extreme Impossible
v1.31 -75% -50% -25% +0% - +25%
v1.40 - -75% -50% -25% +0% +25%
v1.50 - -50% -25% +0% +25% +50%

At the same time, the game also needs to choose the magical Realm from which defenders will come, which is determined by another random roll. In the official game, Mysterious Caves always feature Icon Nature.pngNature creatures (due to a bug in the game code), but in v1.40+ there's a 50 - 50% chance of encountering either Icon Nature.pngNature or Icon Chaos.pngChaos monsters here. The cost of each individual creature is listed in the following table, with changes introduced by the Unofficial Patch 1.50 (if any) highlighted under the originals (which also still apply in Insecticide):

Realm Possible Defenders
Icon Nature.png 100%  (v1.31)
Icon Nature.png50% (v1.40+)
Unit Unit Icon WarBears Transparent Unit Icon Sprites Transparent Unit Icon EarthElemental Transparent Unit Icon GiantSpiders Transparent Unit Icon Cockatrices Transparent Unit Icon Basilisk Transparent Unit Icon StoneGiant Transparent Unit Icon Gorgons Transparent Unit Icon Behemoth Transparent Unit Icon Colossus Transparent Unit Icon GreatWyrm Transparent
Cost 70 100 160 200 275 325 450 599 700 800 1000
300 150 225 600
Icon Chaos.png 50%  (v1.40+) Unit Unit Icon HellHounds Transparent Unit Icon FireElemental Transparent Unit Icon FireGiant Transparent Unit Icon Gargoyles Transparent Unit Icon DoomBat Transparent Unit Icon Chimeras Transparent Unit Icon ChaosSpawn Transparent Unit Icon Efreet Transparent Unit Icon Hydra Transparent Unit Icon GreatDrake Transparent
Cost 40 100 150 200 300 350 400 550 650 900
Icon Death.png 75% Unit Unit Icon Skeletons Transparent Unit Icon Zombies Transparent Unit Icon Ghouls Transparent Unit Icon Demon Transparent Unit Icon NightStalker Transparent Unit Icon Werewolves Transparent Unit Icon ShadowDemons Transparent Unit Icon Wraiths Transparent Unit Icon DeathKnights Transparent Unit Icon DemonLord Transparent
Cost 25 30 80 80 250 250 325 500 600 900
125 200 250
Icon Life.png 25% Unit Unit Icon GuardianSpirit Transparent Unit Icon Unicorns Transparent Unit Icon Angel Transparent Unit Icon Archangel Transparent
Cost 50 250 550 950
Icon Sorcery.png % Unit Unit Icon PhantomWarriors Transparent Unit Icon Nagas Transparent Unit Icon AirElemental Transparent Unit Icon PhantomBeast Transparent Unit Icon StormGiant Transparent Unit Icon Djinn Transparent Unit Icon SkyDrake Transparent
Cost 20 120 170 225 500 650 1000
50 325 200

If the encounter budget is insufficient for any creature in the chosen Realm, the Mysterious Cave has no defenders and the encounter is defeated the first time any unit attempts to enter the square. Otherwise, the game divides the final budget by a random integer in the range of 1 - 4 (or 1 - 6 in patches v1.50 and later), and selects the most expensive unit in the chosen Realm which costs less than this value. This will be the "primary" creature featured at the Mysterious Cave. If no monsters qualify, a new random number will be chosen, repeating the process up to 200 times to ensure that if the budget is high enough to afford any creatures, there will be some.

Once the primary creature type is chosen, the game divides the budget by the cost of this unit, rounding down, to determine how many of these monsters will actually be in the Mysterious Cave. However, this will never be more than 8 (or 6 in the v1.50+ patches), and if it is more than 1, there is a 50% chance that it will be reduced by 1. These limitations significantly increase the likelyhood of encounters featuring more than one type of monster.

The type of the primary creature(s) guarding the Mysterious Cave can be revealed by any scouts that move onto its square. This information will then subsequently be available through the Surveyor (F1) tool. Insecticide also vaguely denotes the amount of these creatures by adding the word "many" to the dialogue if there are 4 or more. The Unofficial Patch 1.50 takes this a step further, using "few" for 3 or 4 units, and "many" for 5 and 6 (the maximum amount in this patch) instead. Neither patch carries these quantities over into the Surveyor (F1) however, which is thus limited to showing the creature type in all game versions.

Secondary Creatures Edit

Finally, the game calculates the remaining budget by subtracting (number of primary monster) × (cost of primary monster) from the initial budget. If this is sufficient for any creature other than the primary monster from the same Realm, it will then proceed to add "secondary" defenders to the Mysterious Cave. These units won't show up in the scouting dialogue, but if a battle is initiated at the site, their type will be displayed by the Surveyor (F1) afterwards (provided that any of them survives).

Similar to the primary guardians, secondary monsters are also chosen using a divisor roll which, just like for primary defenders, can be rerolled up to 200 times to ensure that as long as the budget is high enough for them, secondary creatures will also be present. However, the range for this random number is not pre-set, as it is for the primary guardians. Instead, the game subtracts the amount of primary monsters already added to the Mysterious Cave from 10 (or 9 in v1.40 and later), and uses this value as the maximum range of the random function. For example, if the Mysterious Cave already has 3 primary creatures, the secondary divisor will be in the range of 1 to 7 (or 1 to 6 in v1.40+).

Again, the most expensive unit (other than the primary monster), which costs less than the remaining budget divided by the random number, will be selected. The rest of the encounter is then populated with this creature, up to the maximum of 9 total units (including the primary monsters), or until the remaining budget is exhausted. That is, the amount of secondary monsters will be the lower of either (9 - amount of primary monsters), or (remaining budget) / (cost of secondary monster).

Multiple Battles Edit

If, during an assault on a Mysterious Cave, the invading army manages to kill a defending unit, but then loses the battle or retreats, that unit will not be restored unless it has the Ability Regeneration Regeneration ability. This means that it is possible to "whittle down" the Mysterious Cave's defenders with several subsequent battles, instead of trying to kill all of them at the same time.

However, any guardians that are not destroyed completely are fully healed at the end of each battle, and will have all Icon Figure.png figures restored to life appropriately. Thus, it is not possible to kill one unit by injuring it repeatedly in each battle - it must be killed completely to ensure that it does not reappear in the next battle.

Treasure Edit

Main article: Treasure

The rewards for conquering a Mysterious Cave depend largely on its defenders: the stronger the creatures guarding it, the better the Treasure. Supreme rewards, such as new Spellbooks, or Retorts, are only found behind the strongest monsters. The game decides the types of Treasure that will eventually be awarded immediately after setting out the monsters, meaning that conquering the Mysterious Cave in multiple battles will not reduce the Treasure found inside. On the other hand, because Treasure specifics are only chosen at the time of the victory, saving before the (final) battle can be useful for rerolling them.

Treasure Budget Edit

To determine the base value of the Treasure, the game first tallies up the guardians. The full cost of the primary monsters is converted into Treasure "points", while secondary creatures only contribute half of their cost. Thus, the formula is (cost of primary monster) × (amount of primary monster) + (cost of secondary monster) × (amount of secondary monster) / 2. In v1.50 or later, the cost of the secondaries is no longer halved, and the full creature cost is used as the base Treasure "budget" instead.
In v1.31 and v1.40 (but not in v1.50), this base "budget" is then put through what is essentially a reverse function of the Difficulty adjustment used to scale the creature budget (see above), so that Treasure value is more or less unaffected by the Difficulty Setting (as in the original game Difficulty is only supposed to scale down monster strength). That is, unless the game is played on the "Impossible" Setting, for which the Treasure is not adjusted downward, meaning that the higher creature budgets here result in more valuable Treasure than on any other Setting.
Finally, the budget receives a percentage adjustment. In the official game and Insecticide, this modifier is random depending on the Plane where the Mysterious Cave is located: on Arcanus, the final budget will be 50% - 125% of the previously obtained value, while Myrran sites will have between 76% to 175% of that. v1.50 uses flat values instead of the random percentages: Arcanian Mysterious Caves in this patch will have exactly their total monster value to spend on Treasure, while those on Myrror receive 125% of this. However, as this patch also deals with Encounter Zones that have no guardians differently than the original game, the final budget is further increased by 30 in v1.50, and by 75 in v1.51+ (note that the v1.50 value can occasionally result in no Treasure being found).
In the official game (and also in Insecticide), if the Mysterious Cave contains no creatures, or if their total cost is below 50, the Mysterious Cave's Treasure budget will be set to exactly 50, which allows for a single Treasure roll (see below). This can yield either Icon Gold.png 10 - Icon Gold.png 50, Icon Mana.png 10 - Icon Mana.png 50, or a single spell with a default Spell Rarity of Common. Unfortunately, spells can no longer be found in empty sites starting with v1.50.

Treasure Types Edit

Once the budget is calculated, the computer starts rolling imaginary 15-sided dice to select the basic types of loot found in the Mysterious Cave's hoard. For each roll, if the remaining treasure budget is less than the "Qualify" value (or the "Cost" in v1.50+); or the maximum number of that treasure has already been created; the die is rerolled. Otherwise, the "Spend" value (or, again, the "Cost") of the Treasure is subtracted from the budget, and the selected Treasure type is added to the pile. As long as there are at least 50 points left, the die is cast again to try and add more Treasure.
v1.31 / v1.40 Treasure v1.50+
"Qualify" "Spend" Distribution Type Max Distribution "Cost"
10 (1) 200 2 in 15 Icon Gold.png Gold Coins - 3 in 15 50 - 1000
10 (1) 200 2 in 15 Icon Mana.png Mana Crystals - 3 in 15 40 (1) - 800
300 400 (2) - 3,000 5 in 15 Magical Item 3 3 in 15 200 (3) - 5,100
400 1,000 1 in 15 Prisoner Hero 1 1 in 15 400
3 in 15 Spell 1 (4) 4 in 15
50 50 Common Spell 150
200 200 Uncommon Spell 600
450 450 Rare Spell 1,350
800 800 Very Rare Spell 2,400
1,000 all
2 in 15 Special
(Spellbook / Retort)
1 (4) (5) 1 (6) in 15 800
(1) : The 50-point minimum to generate any kind of Treasure still applies.
(2) : If the remaining budget is lower than 400, the amount spent can be reduced below this.
(3) : Magical Items still require 300 points remaining to be added to a hoard even in v1.50.
(4) : Spell and Specials are mutually exclusive.
(5) : Specials may only be added once, but the amount of picks added (up to 2) depends on the remaining budget.
(6) : There is a further 45% chance that this Treasure type is rerolled regardless of remaining budget.
As noted in the table, Special Treasure can only be added once to a hoard (removing any Spell in the process). When this type comes up on the roll, if the budget is sufficient, the game checks whether it is also enough for 2 "picks". This requires 2,000 points in the original game, and respectively 1,600 in v1.50+. Should this be the case, both "picks" are added, otherwise only one. In the official game and Insecticide, adding a Special also means that all other Treasure is ultimately discarded from the pile.
For Treasure types that have a value range, these are tied to the budget and will be determined at the same time. While this means exact amounts for Icon Gold.png Gold and Icon Mana.png Mana, for Magical Items it is a maximum value instead (which, in v1.50+ will actually be 120% of the Treasure points spent).
In the case of Spell rewards, another random roll is made to determine a default Spell Rarity between 1 and 4 (Common through Very Rare). "Qualify" and "Spend" values are used according to this rarity. However, versions 1.31 and 1.40 will actually add up multiple "Qualifying" rolls of this type, up to the maximum spell rarity of 4 (Very Rare Spell), at which point any further Spell type results of the d15 are immediately rerolled instead. v1.50 removes this behaviour altogether, and can not overwrite an already set rarity with another. Neither version will try to award a lower default rarity if the original roll does not "Qualify".

Treasure Specifics Edit

  • Icon Gold.png Gold and/or Icon Mana.png Mana Crystal piles can appear multiple times in the Mysterious Cave's Treasure, and their amounts are determined at the start of the game (added together).
  • The quality of a Magical Item reward is supposed to scale with remaining treasure points, but in version 1.31, the program only manages to constrain the item's quality in the case of a "Failed Special". Typically, then, the wizard only needs the Spellbook ranks that an item demands, for it to be eligible to (randomly) appear in a Mysterious Cave. Full lists of pre-fab items and their arbitrary rank requirements can be found here, in the article on Treasure. The articles on Magical Items and Encounter Zones also examine in detail how the items are actually chosen.
  • A Prisoner, a most uncommon find, might also be held at the Mysterious Cave. This individual will be one of the 25 non-champion Heroes in the game, drawn at random from those who are not already in the Wizard's service or defeated. The captive V.I.P. will offer to join for no initial cost, out of gratitude for being rescued (however, their upkeep won't be free unless they bear the Ability Noble Noble trait). Before v1.50 however, if the victorious army stack is 9 units deep, or the Wizard already controls 6 Heroes, "Absolutely Nothing" will appear in the Prisoner's place.
  • For Spell rewards, the game will first enumerate the Realms available to the Wizard based on their Spellbooks, and choose one randomly out of these. The Icon Arcane.pngArcane Realm was supposed to always be valid for this for any Wizard, however a bug in the program (before v1.50) only allows these spells to be found if the player possesses either of the (completely unrelated) Alchemy or Warlord Retorts. A random spell is then chosen from the selected Realm matching the default Spell Rarity set out at game creation (see the Spell section of the Encounter Zone article for exceptions). If this spell is already known, the game will sequentially try to award all other spells of the same Realm and rarity. If that also fails, it increases the rarity (wrapping around from Very Rare to Common), and checks each spell in succession until it finds one that is not yet known. Only if all spells of the chosen Realm are known will MoM pick another color to try. There is no replacement reward for Wizards who already know all of the spells available to them based on their books.
  • When a Special is generated, there is a 74% chance that it will be a Spellbook, and a 26% chance that it is a Retort. Retorts that cost 2 picks can only appear at a site with 2 Specials, and will cost both Specials. The Myrran Retort cannot appear in Treasure, and the prerequisites for all other Retorts are ignored. Spellbooks found in a Mysterious Cave will always be of a random type (Wizards possessing any Icon Life.pngLife books cannot get Icon Death.pngDeath, and vice versa). Because a Wizard cannot possess more than 13 Spellbooks and 6 Retorts in a single campaign, any Special reward above these will instead be replaced by a Magical Item with a maximum value of Icon Mana.png 1,200 (or Icon Mana.png 2,000 per "pick" lost in v1.50+).

Rampaging Monsters Edit

Main article: Rampaging Monster

Any Mysterious Cave that has not yet been cleared of defenders is a possible source for Rampaging Monsters.

Difficulty Budget Frequency
Intro Turn x 0.4 ~1/50 turns
Easy Turn x 0.4-0.8 ~1/30 turns
Average Turn x 0.4-1.2 ~1/20 turns
Hard Turn x 0.4-1.6 ~1/14 turns
Impossible Turn x 0.4-2.0 ~1/10 turns

Starting from turn 50, there is a chance for Rampaging Monsters to be generated from a random still-populated nonIcon Life.pnglife Encounter Zone; although only Mysterious Caves that are on the same continent as a Town controlled by any player are valid for this procedure. Both the frequency of this event, and the strength of the monster group created, are random, with limits controlled by the game's Difficulty Setting. The frequency is also increased if the only remaining Neutral Cities are not on the same continent as any Wizard's Towns (resulting in the failure of creating Raiders).

The Realm of the Rampaging Monsters will always match that of the source Encounter Zone, and the process uses a creature "budget" similar to that of generating site guardians. This budget is determined by the turn number and Difficulty and, in the original game, is halved if the Rampaging Monsters are spawned on the same continent as an AI wizard's Fortress (provided that the human player's capital is not also on that continent). The Insecticide patch increases the budgets by 25% in general, and provides a new option to further double them ("Monsters Gone Wild").

Unlike site guardians, the process used for generating Rampaging Monsters does not use divisors, and is not limited to 2 types of monsters. The game will simply select random monsters one by one from the matching Realm until it uses up the allocated budget.

Defeating a Mysterious Cave Edit

When the inhabitants of the Mysterious Cave are defeated, and their Treasure is claimed, the Mysterious Cave is immediately removed from the map.