Roleplayer #29, November 1992


Tools & Techniques for Balancing Magical Adventures

by Charles Wheatley

Achieving a balance of power between mages and non-mages requires a setting where both types can use their talents to be heroes. Since magic depends upon mana, a mage's power can be adjusted to fit the adventure by modifying the mana. Following are a few ways to achieve this.

Different Mana Levels

The most obvious balancing technique is to adjust the mana level (none, low, normal, high and very high) as stated in the Basic Set and GURPS Magic. When mages get too powerful, move the action to a region of lower mana and vice versa. This technique can be fine-tuned by creating levels of mana between the standard ones, for example, medium mana with a -3 spell casting penalty. However, traveling to a new location to change the mana level gets tedious, and mage characters may feel persecuted whenever the action moves to a low-mana area ("Why spend points on spells if the GM is just going to lower the mana?"). Creative GMs will want other techniques to achieve game balance and challenge all players.

Random Mana Levels

An alternative to fixed mana levels is to randomly vary the mana level around an average. For example, if the average mana level is normal, the GM could roll 2d to determine the exact mana level with 2 = no mana, 3-5 = low mana, 6-8 = normal mana, 9-11 = high mana and 12 = very high mana. The time between rolls can be fixed or also determined randomly – e.g., roll for a new mana level every 3d hours.

Randomness makes the mana more like the weather – you know spring is generally pleasant but it's still difficult to predict the exact temperature a week away.

A compromise technique, allowing the PCs to better predict mana levels, uses a die roll to base the next mana level on the current mana level and the normal level of mana in the area. The roll gives the direction and magnitude of the change.

For example, a roll of 1-3 on 1d moves the mana 1 level in the direction of the area's normal mana level (if the mana level is already normal for the location, there is no change). A roll of 4-5 produces no change in the ambient mana, and a 6 produces a change of 1 level away from normal level. If it's exactly at normal level, roll randomly for direction.

Turbulent Mana

Turbulent mana is an area in flux, like the wind or sea during a storm, where the mana moves randomly and rapidly, making magic very uncertain. At the moment a spell is cast, a huge wave of mana could come smashing down on the caster causing a critical failure. The game effect is to add 1 to the caster's die roll for each level of turbulent mana. A roll greater than 18 is a spectacular critical failure!

Turbulent mana may have a fixed number of levels, or the current level may be determined by a die roll each time a spell is cast. For example, a moderately turbulent area might add 1d-4 (minimum of 0) to a caster's spell roll.

Turbulent mana is an effective method of making magic riskier and less certain, especially for mages with every spell at 17 or more. By localizing the effect, the GM can discourage magic use in a particular town or building, to give non-mages a chance to shine. Perhaps non-mages built towns at these locations of turbulent mana to prevent exploitation or domination by mages.

Mages will usually notice that turbulent mana is "peculiar" when encountering it – roll versus IQ + Magery + average level of turbulence. However, the potential disaster awaiting should be hidden until spell casting begins, at which time the GM's generosity will determine the warning to the caster.

Cyclic Mana

This technique has many variations, all based on the premise that the mana level cycles between high and low, like the seasons or the tide. Every variation creates a unique adventure setting. Awesome portents could be related to the mana changes, which may be caused by or only coincide with astronomical events. The knowledge of when these changes occur could be the object of great quests. Predictions based on lost knowledge might be viewed as prophecy.

The Period of the Cycle

The primary factor that describes cyclic mana is how quickly the mana level rises and falls.

Long Cycles. A cycle of thousands of years could foster a civilization that reaches its pinnacle during the period of high mana, only to crumble into barbarism as the "magic" dies. The PCs could explore ruins of cities with mysterious powers built during the "high magic." Will they recognize the dangers and rewards as they adventure on the brink of the magic's return?

Medium Cycles. A 100-year or shorter cycle may produce a society where older people remember when the magic used to be high (or low). The young may doubt the stories (is grandpa senile or did dragons really exist?). Governments may be very unstable as the mages and non-mages alternately rise to power. When the cycle time is in the range of 10 years or less, alliances between mages and non-mages would protect each group when the other is weak.

Short Cycles. A cycle of 24 hours could give rise to a culture where the work day is defined by the mana level rather than the sun. Mana "noon" would be peak mana and "midnight" no mana. If the mana "noon" doesn't match the solar noon, the mages who work only during the evening could give rise to rumors among the non-mages (what do those mages really do while we're asleep?). A cycle of less than a day is easier to track if it divides evenly into the number of hours in a day – i.e., 12, 8, 6,4, 3, or 2 hours for a 24-hour day.

The Mana Extremes

How much the mana fluctuates is almost as important as how often. The mana level doesn't have to oscillate only between low mana and high mana. If the GM wants mages to always have a chance of using magic, the minimum mana level is low mana. To prevent non-mages from ever using magic, the maximum level must be high mana.

A world that rapidly fluctuates between no mana and very high mana would be an extremely unstable place. A place that only alternated between low and normal mana would be fairly stable magically, especially if the changes were very gradual. And a normal- to high-mana cycle gives non-mages a reason to learn spells.

Cycle Shapes

The mana cycle does not have to follow a smooth sine curve. Extended periods of low mana with short bursts of high and no mana would give rise to many legends about "the times of power" and "the times of weakness."

The Speed of the Transition

Does the mana level change from low to normal in an instant, or does the spell penalty adjust gradually 1 at a time? A smooth transition over a long period may not even be noticed by most people, while an instantaneous jump from no mana to high mana could mark the beginning of a new age. A rapid mana-level change could create Turbulent Mana (see p. 28) for an extended time before and after the change.


In this world, the mana varies like weather, with each of the four mana "seasons" lasting one calendar month for a mana cycle of four calendar months. Roll 3d on the following table to determine the exact mana level based on the current "season." Then roll 3d again to determine how many hours pass before rolling for mana level again. For example, in mana spring, a roll of 14 means the mana level is high.

Mana Season

Mana LevelFall/SpringSummerWinter
Very High17-1814-18

The average mana level is normal in fall and spring, high in summer, and low in winter. This allows the mages to behave normally half of the time, compete with non-mages one quarter of the time, and depend on non-mages the other quarter of the time. It certainly spices up the interrelations in an adventuring party.

Mana Sinks

A mana sink is a person, place or thing that attracts and absorbs magical energy. By absorbing mana, it can precisely limit when and where magic is viable. A sink can subtly limit magic use or can be the object of a whole adventure. The exact nature of a mana sink is defined by how it absorbs and dissipates magical energy.


Types of Mana. A mana sink may absorb magical energy from spell castings, Powerstones, magic items, the surrounding mana, a character's fatigue or any combination of these as determined by the GM. Sinks can also be aspected so they only absorb or not absorb the energy from certain spell colleges. A sink created in a volcano may absorb only fire college spells – or it may absorb only water college spells and dissipate the energy as fire college spells.

Range. The range determines how much area is affected by the sink. A very large range effectively makes a whole area low or no mana. A very small range provides a movable, localized non-magical area. Both extremes make it easy for the GM to track whom the sink affects. To keep the players guessing why spells are failing, the GM should use a sink with a range of 5 to 50 hexes. The drawback is that the GM must constantly monitor the hex map to determine who is within range.

Power. The power of a sink determines when the sink absorbs the energy. A truly potent sink would absorb all magical energy within its range, even mages' fatigue! To precisely define a sink's power, the GM assigns it a skill level that is used in a contest of skills versus the caster to determine who gets to use the mana in the spell.

Or a sink's power might depend on its distance from the caster and/or the caster's roll. An example is a sink that will not absorb the power from a spell casting unless the caster makes his spell roll by less than 10 minus the number of hexes from the sink. A caster standing 4 hexes from the sink would need to make his spell roll by 6 (10 minus 4) or more to prevent the sink from absorbing his spell energy.

Capacity. A sink, like a Powerstone, usually has a maximum amount of energy it can absorb. When this capacity is reached, it could simply stop absorbing energy, it could redirect the excess energy . . . or it might explode, summon a demon or teleport everyone 100 miles away! A hum or glow as it nears capacity is a good dramatic effect.

Maintained Spells. A mana sink will not undo the effects of a permanent spell although it may affect maintained spells. If sinks affect maintained spells, the amount each spell casting roll was made by should be noted. Then if the mana sink is in range when the spell is renewed, it will affect the renewal as if the original spell casting were made under the current conditions. This is quite complex and the GM will need to keep good records if he uses this system.

Tradeoff Skill versus Power. A mana sink absorbs the full power needed to cast a spell before any reductions for high skill or other factors. The additional power above the mage's fatigue and Powerstones comes from the mana channeled by the mage.


How a sink uses the mana can be as fascinating as how it absorbs it. A sink may simply dissipate mana at the same rate a Powerstone charges, or it may use the mana to power a spell as per a self-powered magic item. The spell might be cast automatically by the sink or may require someone to cast it. A sink would be a excellent protective charm if after absorbing magical attacks it releases the energy as a counter-attack.

The mana sink could discharge its mana like a Powerstone, although this can be abused by providing mages with a Powerstone that can be recharged by casting any spell. Fast-charging Powerstones can be very unbalancing unless they have some drawback, such as exploding for 4d damage on any spell casting roll over 15.

Sinks in Various Mana Levels

The surrounding mana level may cause sinks to charge or discharge. A sink from a high-mana area might "leak" or discharge energy in lower mana while absorbing energy in a very-high-mana environment. The range and power of the sink may also be affected by the prevailing mana level. Perhaps the sink ceases to function at lower mana levels and actually increases range and power at higher mana levels. Or the mana level could have absolutely no effect on the mana sink.

As an example, consider a sink that behaves like a Powerstone and absorbs mana at 1 point per hour to its capacity only in high or very high mana region. If these are the only Powerstones available, mages will conserve them when traveling in normal or lower mana areas. A trade network might recycle "used" Powerstones to be "refilled" in high mana areas. The GM could use this network to precisely dole out the power available to mages.

Detecting and Analyzing Mana Sinks

A mage's ability to detect a mana sink depends on when the mage encounters the sink and how long the GM wants to keep the PCs guessing. Casting an Analyze Magic spell can be difficult if the sink absorbs the spell's energy.

Outside its effective range. The GM may provide a mage information on a mana sink if a very good perception roll is made when first seen. The GM should not call it a mana sink but should describe it, perhaps, as "a depression in the mana."

Within its effective range. A perceptive mage may feel a "tug" in the direction of an especially powerful mana sink.

Using magic in range of a sink. When a spell is cast, the mage will detect the sink if it successfully absorbs the magical energy. If the mage wasn't expecting the sink, the GM simply tell the mage the energy was expended but the spell didn't seem to work. Once the mage is concentrating on what happened to the energy, the GM can add that it went toward the sink instead of into the spell.

If the sink didn't absorb the magical energy, the mage may still feel a tug on the casting in the direction of the sink. The closer the sink comes to absorbing the energy, the more noticeable it will be. One option is to roll versus IQ minus the absolute value of the amount the casting roll succeeded or failed. For example, a mage with an IQ 12 needs to roll a 13 for the spell to succeed against the sink – she rolls an 11. The GM may secretly roll against IQ minus (12-2) = 10 for her to notice what happened to the magical energy.

Mana Sinks Versus Powerstones

A Powerstone is a special-case mana sink that slowly absorbs energy only from the surrounding mana and discharges it to any source for any purpose. A mana sink can be made that absorbs energy from Powerstones.

Example – A Person as a Mana Sink

A great way to moderate PC mages is to introduce an NPC who is a mana sink. In my Yrth campaign, I introduced a Nomad woman with bright red hair who thought she was the daughter of the fire god. The PCs, averaging about 130 points, thought she was nuts, but they allowed her to join them because they needed another good fighter. However, unknown even to her, she was a mana sink.

Any spell-casting roll must succeed by (15 minus the number of hexes from her to the caster) for the spell to work, otherwise she absorbs the energy in the casting and prevents the spell from working. For example, a PC mage 8 hexes from her must make his spell roll by at least 15 minus 8, or 7! The energy powers her ability to automatically heal herself when injured as per the Major Healing spell and to increase her ST as per the Strength spell when under stress. She starts to glow as per the Light spell when charged to 40 points, with each additional point becoming more painful and causing a brighter glow until at 50 points a 10d explosive fireball (yes, 10d!) erupts with her at the center.

She "leaks" 1 energy point per hour in no mana, 1 point per day in low mana and no points in normal mana. She charges 1 point per day in high mana and 1 point per hour in very high mana. Powerstones of less than 50 points will not charge within 6 feet of her.

Because she was a party member, it was normal for her to move among the PCs when they were casting spells. The PC mages were completely perplexed when their spells – seemingly at random – didn't take effect but still cost them energy. This mystery kept the whole party entertained and made the fighters in the group happier and more valuable because their cold steel always worked. Soon they began to wonder if the "daughter of the fire god" story might have some truth in it after all.

After discovering and analyzing the source of the problem, they weren't sure she should stay with them because she interfered with their mages. She proved her worth, however, when the party ran up against a 250-point mage. At first they kept her back so their mages could attack. After almost losing a few comrades, they realized she could nullify the opposing mage! They maneuvered her within range of the mage, then attacked before he could discover what had happened to his magic. The mage was vanquished and they all lived happily (mostly) ever after. The fire woman
has since left them for other adventures. But not before teaching them that ingenuity can turn an apparent handicap into quite an advantage.

Mana-Eating Creatures

Another way to tone down PC mages is the presence of creatures known as "mage-eating mists."

The "mists" are 2- to 4-hex-radius, slightly luminous, viscous clouds that "feed" on ambient magical energy. Spell casting, Powerstones, high mana and other concentrated mana sources attract them; a mana burst allows them to reproduce by splitting into two creatures. Six to eight years after splitting, the mature creatures begin to search for concentrated mana sources. If unable to find a high-mana source in 8 to 12 years, they slowly dissolve into various gases. They will not voluntarily enter a low- or no-mana area because their movement is only 1 in low mana and they hibernate in no mana. Treat them as clouds of water vapor to determine means to damage them – i.e., fire and high wind cause damage but a sword will not. They react to injury by fleeing.

Each creature has 2 HP per hex size, IQ 4, HT 14, a movement of 15 and can detect mana sources at great distances, especially large ones. The "mage-eating" reputation came from their habit of accidentally suffocating mages (the cloud is an asphyxiant) when they engulf them to feed on their Powerstones. They absorb 1 point of energy per 10 seconds until all of the mana is consumed or they have eaten 2 points per hex size. Because the release of mana in spell casting is instantaneous, they cannot feed on it, but are still attracted by it.

Mages can be limited by using these creatures to force them to rely only on their own fatigue. Or, since they like mana, a GM can use them to make magically powerful places risky to mages. Perhaps a very intelligent specimen can be trained to be a guardian or watchdog. Most importantly, when the "mist" is around, the mages are always paranoid.

Mana Nuggets

So far this article has described ways to limit mages. However, sometimes the party gets in over their heads, uses up all of their Powerstones, and need some surreptitious help from the GM. Mana nuggets are a way to provide it.

Mana ebbs and flows sometimes condense to form nuggets. These are essentially one-shot Powerstones that can recharge normal Powerstones. A mana nugget can be used as a normal Powerstone that doesn't recharge and crumbles when all of the power has been drained. However, when a nugget touches a normal Powerstone, it will drain its charge into the Powerstone up to its capacity. Mana nuggets make large Powerstones more useful by eliminating the long times required for recharging. This in turn makes high-cost spells more common.

Naturally occurring nuggets can be an effective deus ex machina for an overly-taxed party of PCs, mere curiosities, or the object of an adventure. The secret to easily creating them would be valuable indeed. Warning: freely distributing these will quickly increase mages' power and unbalance the magic system.

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