Skills

How Skills Work
Criticals and Fumbles
Automatic Successes
Modifying Skills
Opposed and Differential Rolls
Standard Skills
Professional Skills

How Skills Work

A skill has a Base Value built on two Characteristics, or on one Characteristic multiplied by two. There is no upper limit to a skill’s value; it can exceed 100 and, in play, characters can expect to see their skills reach such heights.

Whenever a character is called upon to resolve some form of test, challenge, or professional ability, 1d100 is rolled and compared with the skill’s value:

Equal to, or less than, the skill indicates a Success

Greater than the skill’s value indicates a Failure

There are certain special cases concerning Success and Failure that should be noted:

Any roll of 01-05 is always a Success.

Any roll of 96-00 is always a Failure, irrespective of how high the skill’s value.

Criticals and Fumbles

A Critical Success is equal to one-tenth of the skill’s value (and this includes skills that receive a modifier – so modified skills may have a greater or lesser chance of a Critical outcome).

A Fumble is a roll of 99 or 00. Skills with a value of 100% or more Fumble only on a roll of 00.

Round fractions up when calculating a Critical Success’s range. For example, if a skill is modified to twice its normal value – from 33% to 66% say, then its Critical range would be a roll of 07 or less.

The precise nature of a Critical or Fumble result is left to the Game Runner to determine. The consequences could be wondrous or dire, depending on the circumstances.

Automatic Successes

There will be some occasions where a roll against a particular skill is just not necessary – either because the task at hand is easily accomplished, or because, with enough time and focus, success is guaranteed.

Riding a horse at a gentle canter across an open meadow is an example of an Automatic Success where simply being skilled in the activity means that straightforward actions do not require any skill rolls to resolve them. A crafter carving a piece of wood into a chair leg is another example where a skill roll is not necessary; it takes time to accomplish, but the craftsman knows how to do the work and, if not rushing, success is assured. A rogue, undisturbed, with a set of lockpicks, can successfully pick the simple lock of a treasure chest given enough time to do so.

Modifying Skills

There are some occasions where a skill roll is required, but the chances of success need to be adjusted to reflect existing conditions. Fleeing bandits, for instance, might require an Athletics roll. But what if the character is fleeing through darkness or through treacherous undergrowth? In such a case the Game Runner can insist on modifying the skill of the character to reflect the circumstances.

Casus Mus uses a series of grades to determine how a skill is modified. These are as follows. Note that two types of modifiers are provided: the first is the default method, and involves a little math, but offers better simulation for scaling, especially where higher skill percentages are concerned. The Simplified Skill Modifier is a simple addition or subtraction, and easier to implement. Choose which method best fits the game but ensure that the same modification system is applied consistently.

Where a character is already suffering a penalty from other circumstances, the hardest Difficulty Grade takes precedence.

Outside of combat, Casus Mus does not provide a definitive list of situations and challenges which can incur skill modifications. What sort of modification is required for any particular skill or context is ultimately up to the Game Runner to decide; according to the capabilities of the characters, their perception of the difficulty of the situation and the dramatic tension at that particular moment.

Opposed and Differential Rolls

Although the basic rules for using skills are very straightforward, there are a multitude of different circumstances that arise during play that require skills to be handled in a slightly different way. The following sections look at these circumstances and situations and show how to handle them.

Opposed Rolls

Skills are frequently pitted against other skills – Stealth versus Perception when a rogue attempts to cut a nobleman’s purse, say; or Deceit versus Insight when the same rogue tries to deny the attempt when she is caught – are good examples of times where skills are matched against each other. These are known as Opposed Rolls and are used where a challenge will result in either win or lose, pass or fail.

An Opposed Roll is determined thus: both participants roll their respective skills. The winner is the one who gains the better level of success. If the participants score the same level of success (a Standard Success each, or a Critical each), then the winner is the one who has the highest dice roll still within the success range of the skill.

Opposed Rolls are frequently used in certain battle situations to overcome the effects of wounds or oppose a combat Combat Maneuvers. They are also used to resist poisons and disease or shrug off the effects of baleful magic.

Opposed Roll Examples

Differential Rolls

Differential Rolls are similar to Opposed Rolls except that instead of a simple win or lose result, the difference in levels of success are calculated. Primarily used for the resolution of combat, Differential Rolls can also be used in other situations where the Game Runner wishes to increase the detailed results of a contest.

Both participants roll against their respective skills. If both participants score the same level of success (a Standard success each, or a Critical each), then there is no other/additional effect.

Compare results on the following table. In combat, a level of success means that participant can choose a Combat Maneuver.

Differential Rolls - Levels of Success

Standard Skills

Athletics (STR+DEX)

Athletics covers a range of physical activities, including climbing, jumping, throwing, and running. Skills rolls for any of these activities are handled by a single roll against the Athletics skill. See Movement in the Game System section for more information on climbing, jumping, and running.

Boating (STR+CON)

The Boating skill covers the operation of small floating craft. on rivers, lakes, and close inshore. Appropriate vessels are generally boats, canoes, or rafts which travel short distances and are unsuited to the rigours of the open sea. Most are propelled using oars, paddles, punts or simple sails; or can even be towed by animals. Ships with large crews or designed for long, overseas journeys are covered under the Seamanship Professional Skill.

Brawn (STR+SIZ)

Brawn is the efficient application of technique when applying raw physical force. The skill covers acts of applied might, including lifting, breaking down doors and contests of strength.

Combat Style (STR+DEX)

Each Combat Style is the skill to use the weapons expected of a career or culture in the setting. Most fighting traditions encompass training in multiple weapons, along with the techniques required to use them all effectively, whether singly or in combination. In addition they often assume a situational element, such as fighting as close order infantry or while mounted. Combat Styles can be very diverse, ranging from, for example, Gladiatorial Combat all the way to Space Marine Mobile Infantry.

Conceal (DEX+POW)

Conceal is the counterpoint to Stealth, being the concealment of large objects rather than the character themselves. For instance, conceal could be used to hide a chariot behind some rocks, or sweep away the wheel ruts it left so its path cannot be tracked. The skill is versatile in application, anything from hiding a scroll in a library to disguising the presence of a trap or secret passage.

Customs (INT x2+40)

Customs represents the character’s knowledge of their own community: its social codes, rites, rituals, taboos, and so on. The skill is used when it is essential to accurately interpret or perform any socially important custom or to behave in a particular way.

Dance (DEX+CHA)

Just about every culture uses dance in some way – either as recreation or as part of important rituals. It might be a court dance, a war dance, or a simple set of movements accompanying a prayer or ceremonial chant. The Dance skill measures a character’s ability to move rhythmically and accurately (to a reasonable degree) when called upon to do so.

Deceit (INT+CHA)

Deceit covers all instances where a character attempts to mask the truth and offer a deception of some kind: barefaced lying, misleading a guard, or even bluffing (or cheating) during a card game. The skill also covers instances where hiding true emotions or motives is necessary (feigning pleasure when one is bitterly disappointed perhaps, or attempting to seem welcoming and open when the opposite is true). Deceit forms a counterpart to the Insight skill and can be used to oppose Insight rolls when others are attempting to discern either truth or motive.

Drive (DEX+POW)

Drive covers the control of wheeled or drawn vehicles, whether by one or more beasts of burden or powered by more esoteric means, such as chariots, sleds, sail carts, or even gasoline cars. A roll is also necessary if the vehicle being driven is drawn or powered by a means different than the driver is used to (horses instead of oxen, or a motor rather than animals for example).

Endurance (CON x2)

Endurance is a character’s capacity to endure physical stress, pain, and fatigue. It measures the body’s ability to deal with potentially damaging or debilitating conditions and is a general gauge of resilience, stamina, and metabolism. Endurance, like its counterpart Willpower, is used in any number of ways, but most specifically to resist the possible effects of injuries, including harmful poisons and disease.

Evade (DEX x2)

Evade is used to escape from observed, impending danger and can be used against Ranged Weapons (by diving for cover, for example), avoiding traps, changing the engagement distance in combat, and generally getting out of the way of a potential physical hazard. It can also be used as a resistance roll for certain types of magic. Using Evade usually leaves the character prone. Those with the Daredevil Combat Style Trait may use Evade to dodge a melee attack without falling prone and, against a ranged attack, they only end up prone if they fail the roll.

First Aid (DEX+INT)

The skill of First Aid measures a character’s ability to treat minor injuries and stabilise more severe ones. First Aid may be applied only once per specific injury and heals 1d3 points of damage.

Influence (CHA x2)

This is a measurement of a character’s ability to persuade others, through personal charisma, into a desired way of behaving. It is used in a wide variety of situations; from changing someone’s mind, to bribing an official or guard. Influence rolls are typically opposed by the Perception, Willpower, or another Influence skill, depending on the circumstances, and are modified by how much a character is trying to influence behaviour. Attempting to persuade a close friend to loan you their horse may be relatively easy. Getting a usually incorruptible bureaucrat to accept a bribe is more difficult.

Insight (INT+POW)

Insight is the ability to read or intuitively define another’s verbal and non-verbal behaviour (such as body language or the manner of speech) to establish their motives and state of mind. Insight is used to determine whether someone is telling a lie (and it can be opposed by the other person’s Deceit skill), or to predict how someone feels about a particular situation. Insight can equally be applied to particular situations as well as other people: is that tavern a haven for trouble? Could the bandits be planning an ambush in the nearby hills?

Locale (INT x2)

Locale measures a character’s understanding of local flora, fauna, terrain, and weather in the area where he or she has spent much of their life, usually within their community. The character knows the common plants, trees, and animals, their properties and behaviour: where the best fish can be found; the movements of game creatures; where to find shelter; the likely weather for the season, and the most common regional dangers. In neighbouring, yet unfamiliar locations Locale should be made one or more grades harder.

Native Tongue (INT+CHA+40)

Native Tongue is the ability to speak and read one’s own language, the one learned while growing up in one’s home culture. Native Tongue measures articulation, eloquence, and the depth of the speaker’s vocabulary. Unlike other skills, Native Tongue is not rolled against directly. Instead, it is treated as a static representation of overall fluency, limiting the level of conversational interaction. This is described in more detail under the Language skill, but starting characters usually begin play fully fluent in their mother tongue.

Perception (INT+POW)

Perception is used for both passive observation and focused detection; whether hunting for something specific, a general scan of an area, or simple awareness of their surroundings. Specific conditions – darkness, for example – may affect the Difficulty Grade of the skill roll depending on the primary senses being used. Strong scents might make an olfactory Perception roll Easy rather than Standard, whereas trying to eavesdrop on a conversation in a crowded and noisy tavern would make the roll Hard.

Ride (DEX+POW)

Ride covers the ability to control and remain mounted on those creatures that are trained to be ridden. The skill can be applied to a diverse range of beasts, everything from mules to elephants; even flying or swimming creatures such as giant eagles or dolphins. Riding an unfamiliar species is always one Difficulty Grade harder; while riding a species of a different medium (a horseman riding a dragon, for example) is two grades harder. Wild, untamed creatures cannot be ridden in a constructive manner until they have been broken and trained to be riding beasts.

Sing (POW+CHA)

Carrying a tune is covered by Sing, anything from monotonous chants through to complex arias. Singing is an inherent part of most cultures, a prime source of entertainment and perhaps used in its rituals. Important songs might be used for courting, inspiring soldiers before battle, or simply recounting a historical deed. The skill reflects the user’s ability to maintain rhythm, keep in key and remember the correct words.

Stealth (DEX+INT)

Hiding out of plain sight, or moving with minimal sound are covered by the Stealth skill. Cover and conditions, such as darkness or loud background noise, improve the grade of the skill according to the specifics of the environment. Similarly, adverse conditions, such as a lack of cover or a quiet night will decrease the skill’s grade. Circumstances also affect the difficulty of the attempt. For instance, a warrior wearing heavy armor can easily conceal themselves behind a wall, provided they stand still or move very slowly, whereas moving quickly might cause their armor to jingle.

Swim (STR+CON)

Without development, the ability to swim is limited to being able to thrash around and keep one’s head above the water for a short time. Higher Swim percentages indicate being able to negotiate deeper and stronger waters, with less risk of drowning. Making a Swim roll thus depends entirely on the conditions. Rough seas, strong currents, white water, and rip tides all reduce the grade of the skill no matter what the character’s affinity for water might be. See Movement for more information on swimming, including calculating swim speeds.

Unarmed (STR+DEX)

Unarmed is a universal Combat Style common to all characters, measuring the ability to defend oneself without the aid of weapons. The Unarmed skill covers the brawling and wrestling techniques known by that culture. As Unarmed is a Combat skill, its Critical and Fumble effects are covered by the rules for combat, as detailed in the Combat chapter.

Willpower (POW x2)

Willpower is a measure of a character’s ability to concentrate, channel their force of will in a particular direction, or harden their psyche to possible mental shock. It is also a measure of personal resolve. The skill is used in all manner of situations where mental resilience is required, and this includes resisting magic. Although not a measure of sanity it can be used to endure traumatic events that would shake even the sanest, stable mind. Willpower is the mental counterpart to Endurance. Again, like Endurance and Evade, Willpower is most often used in Opposed Rolls. When used as a Standard test, a Critical Willpower roll indicates that the character has hardened their mind and spirit to the extent that no further attempts to influence him, or shake their resolve, will work. In the case of resisting magic, a Critical Success means that no further mentally afflicting spells cast by the opponent have any effect on the character for the remainder of that encounter.

Professional Skills

Professional Skills differ between characters and represent more specialised forms of training and experience. Some Professional Skills are gathered through cultural background and a character’s Career, as the name suggests. Although they differ between characters they work in the same way as Standard Skills.

Acting (CHA x2)

Acting governs the art of being able to impersonate and convey a completely different character, whether in a staged performance or in a social situation. The actor portrays a personality and mannerisms different to their own in a convincing manner. Coupled with the Disguise and Deceit skills, this is a powerful way of becoming someone else entirely.

Acrobatics (STR+DEX)

Acrobatics covers acts of balance, gymnastics, juggling, and tumbling. The skill can be used to impress an audience, but also to help mitigate damage from falls. With a successful roll, a character can move at full speed and sure-footedly across an unstable or narrow surface. If trying to mitigate damage from an unexpected fall, a successful Acrobatics roll halves any damage sustained. In addition, if the roll is successful and the character does not suffer a Serious or Major Wound due to the fall, the character lands relatively safely and is not prone. Acrobatics can be substituted for Evade if the situation warrants it. The benefit of this is that the character automatically regains their footing rather than being rendered prone.

Art (POW+CHA)

There are many specific art forms. Painting to Poetry; Literature to Sculpture. A character chooses an Art specialisation when taking this skill. Subsequent Art forms are advanced separately. A roll is made whenever a character must impress or convince through their artistic medium.

Binding (POW+CHA)

The Binding skill is used for Binding Hedge Magic spells into objects, and is described in the Binding chapter.

Bureaucracy (INT x2)

Understanding administrative procedures, records, and unspoken conventions are covered by the Bureaucracy skill. It is used to interact with officials or discover pertinent civic information. Depending on the sophistication of their culture, bureaucrats need not necessarily be literate. Whenever red-tape or administrative landscapes need to be navigated, a Bureaucracy roll is necessary.

Commerce (INT+CHA)

Commerce is used to evaluate the worth of goods and commodities and to trade them for the best possible price. It is also used to understand the intricacies of business transactions in addition to securing a profit. A further use is in finding the best way to dispose of stolen and illicit goods – again for the best possible price. Commerce is obviously used when trading and it can be opposed by either an opponent’s Commerce skill or Willpower, reflecting the opposing side’s attempts to further the deal in their favour. It is also used to judge the market value of goods, gaining an idea of price, and where it will be best traded.

Courtesy (INT+CHA)

This skill covers understanding how to act appropriately in a social or formal situation: modes of address, rituals, and conventions of behavior, and so forth. It includes everything from who to bow to and when, to how low; from when to use a particular title to when it is appropriate to act informally.

Craft (DEX+INT)

Each Craft is a specialised form, and there are as many crafts as there are professions for them. Like Art, Craft is used to create the subject item. How long it takes depends entirely on the nature of the product: weaving a rug takes longer than throwing a pot, for instance, but time is not necessarily the most important factor: it is the skill of the crafter, the quality of the resources and attention to detail.

Culture (INT x2)

Culture is the more specific form of the Standard Skill of Customs, relating instead to societies foreign to the character’s own. Each Culture skill must be given a particular nation or society to which it applies. Mechanically it works in the same way as the Customs skill.

Disguise (INT+CHA)

Effecting a convincing disguise, using appropriate materials (costumes, cosmetics, wigs, or hairpieces), is covered by the Disguise skill. Creating the disguise requires time and attention to detail, as well as access to the right materials to make it convincing. If some, or all, of these elements are not present then the Disguise roll’s Difficulty Grade is made one or more steps harder. Disguise can be augmented with Acting to enhance the overall effect of a deception (vice versa when performing) and so the two skills are complementary.

Engineering (INT x2)

The design and building of large-scale structures, from houses to bridges, gates to siege engines, is in the remit of the Engineering skill. Rolls are necessary when planning large-scale projects to ensure correct construction but are also made when an engineer wants to assess a structure’s integrity for whatever reason (state of repair or weak spots, for example).

Forgery (DEX+INT)

The Forgery skill permits the creation or falsification of official documentation.

Gambling (INT+POW)

The Gambling skill measures a character’s competence in games of chance and especially where money is staked on the outcome. It is used to assess the odds of success or failure or spot when someone is cheating. The skill can be used in an opposed or unopposed manner, depending on the situation. Spending the night in a faceless gambling den might only require a straight test, whereas a high stakes dice game involving notable personages may instead require several Rounds of Opposed Rolls.

Healing (INT+POW)

Healing is the in-depth knowledge of medical procedures, based on cultural practices and is used to treat more serious injuries (typically those where Hit Points are at zero or less). In a Primitive or Barbarian culture for instance, healing will be based on the knowledge of herbs and natural cures. In a Civilised culture, drugs and more advanced treatments will be more common. In all cultures Healing includes the ability to set bones, suture wounds, and so forth. Obviously applying Healing requires appropriate resources, and most practicing healers will have such things at hand (needles, gut or thread for sutures, herbs for poultices, and so forth, or a medical kit for modern settings).

Hedge Magic (POW+CHA)

The Hedge Magic skill is used for casting the spells described in the Hedge Magic chapter.

High Magic (POW+CHA)

The High Magic skill is used for casting the spells described in the High Magic chapter.

Language (INT+CHA)

This skill covers the speaking and comprehension of a language other than the character’s own. The skill is treated as a static representation of overall fluency. 1-25% a few basic words, 26-50% simple sentences, 51-75% fluent for general conversation, 76+% able to converse eloquently. Its value is used by the Game Runner to limit the level of spoken interaction when the players converse with personalities in the game. It can also be used as a cap for certain other skills (such as Bureaucracy), where Language may be a limiting factor. In such a case, a skill like Bureaucracy cannot exceed the skill value of the Language being used.

Literacy (Specific Language) (INT x2)

Speaking a language fluently does not mean one can read and write it. Literacy is a specific skill and different societies display different levels and approaches towards it. In some, literacy is reserved for the nobility, bureaucratic or religious classes. In others it is unknown with oral traditions prevailing instead. In modern or futuristic societies literacy is learned by default and does not require a separate skill.

Lockpicking (DEX x2)

Lockpicking is the ability to open a mechanical locking system without the aid of a key or other device made specifically for the lock. It includes the techniques of levering open bolted or barred doors and windows without causing damage. Lockpicking may also be used to lock a door, chest, and so on, when no key is available.

Lore (INT x2)

Lore covers a specific body of knowledge which must be chosen when the skill is first learned. Alchemy, Astrology, Astronomy, Geography, Heraldry, History, Midwifery, Mineral, Monsters, Politics, Religion, Strategy and Tactics: these are all typical examples of Lore skills. Skill in a Lore means the character understands its fundamentals, how it can be applied to immediate challenges and problems, and can use the Lore to recall useful information.

Mechanisms (DEX+INT)

Mechanisms represents the knowledge and skill to assemble and disassemble mechanical devices, such as traps. The skill of Mechanisms generally involves the creation of delicate contraptions with small working parts, as opposed to Engineering, which deals with massive constructions. It is a distinct discipline from Lockpicking and cannot be interchanged with that skill.

Musicianship (DEX+CHA)

Musicianship covers the playing of musical instruments; from a simple reed pipe to a complex stringed instrument such as a harp, and each iteration of Musicianship is applied to a group of similar instruments. A musician who can play a reed pipe can also play a flute, panpipes, or a recorder because the fundamentals are the same. They could not, however, play a harp or lute.

Navigation (INT+POW)

Whether using prominent landmarks, the stars, or the varying taste of seawater, the ability to accurately direct travel is covered by the Navigation skill. Each Navigation skill covers a specific region or environment, such as Open Seas or Underground for example. It should be made during unusual journeys or when in completely unfamiliar territory.

Oratory (POW+CHA)

Oratory is the art of delivering a speech to a large group of people with the aim of conveying or swaying a point of view. It is a skill frequently used by politicians to drive home a policy, but is also used by commanders to inspire troops and impose discipline on the battlefield. Wherever mass persuasion is needed, Oratory, rather than Influence, is used.

Pilot (DEX+INT)

The Pilot skill permits the control of a specified class (such as gliders, prop-driven planes, jet engines, and so on) of flying vehicles.

Politics (INT+CHA)

Characters possessing the Politics skill understand how to navigate and negotiate the corridors of government at local and national levels.

Research (INT+POW)

Research uses various resources (such as a library, archive, and so on), to discover desired pieces of information.

Seamanship (INT+CON)

This skill is used in the same way as Boating but is instead applied to large waterborne vessels powered by sail or banks of oars. It also covers the maintenance and upkeep of a ship: assessing when repairs are needed, where it is safe to anchor, the dangers of violent weather, and so forth.

Seduction (INT+CHA)

Seduction is the romantic or sexual persuasion of another person, a skill very different to Influence. It uses explicit signals – verbal and non-verbal – to elicit a sexually positive response. It also takes a significant amount of time: successful Seduction may take hours, days, or weeks to achieve depending on the morals of the target, who can always attempt to resist Seduction with Willpower.

Sleight (DEX+CHA)

Sleight covers attempts to palm or conceal small objects (legerdemain and prestidigitation) and includes attempts to pick pockets, cut purses, or cause a visual distraction. Naturally, it is an essential thieves’ skill.

Streetwise (POW+CHA)

Streetwise represents knowledge of places and social contacts within a settlement. It covers everything from identifying potentially dangerous neighbourhoods, to finding local services – legal or illegal. How long a Streetwise attempt takes depends on what is sought. Finding a good inn will take less time than locating a fence for stolen goods or a fake trading permit.

Survival (CON+POW)

This skill covers surviving in a rural or wilderness environment where the benefits of civilisation are absent: foraging, building a fire, finding shelter or a safe place to sleep. When properly equipped, rolls are usually unnecessary since the character may be carrying a tent, food supplies, and so on. Only when separated from their equipment or when environmental conditions turn bad does it become essential to use this skill. A roll is usually made once per day in such conditions.

Teach (INT+CHA)

Teach allows the user to pass on their knowledge and techniques in an easy to understand and constructive manner. Without this skill even the most capable of masters will suffer problems instructing others.

Track (INT+CON)

The Track skill is used for tracking any form of game or quarry. It uses both obvious and ambiguous signs of passing to remain on the quarry’s trail, including footprints, bruised leaves, scattered pollen, displaced rocks, and so on; small, tell-tale signs that are invisible to the non-skilled. Track rolls need to be made periodically, especially if conditions change abruptly (a rain shower, for example, will disturb certain signs). How often depends on how cunning the quarry has been. Conceal rolls can be used to oppose a Track roll.

Based on Mythras Imperative, Written by Pete Nash and Lawrence Whitaker, and published by The Design Mechanism, Copyright 2023.

Material on this site not covered by other ownership or copyright statements is Copyright © 2024 Robert Prince.