I love fantasy games, and in particular modern fantasy; however, magic systems are often a make-or-break issue for me. Let's be honest, it usually a break issue. Only a very few magic systems really work, and the number of systems that actually excite me could probably be counted on one hand (Ars Magica, Unknown Armies, Sorcerer and Buffy the Vampire Slayer immediately jump to mind).
Books on writing fantasy often discuss the creation of interesting magic systems. A magic system needs to be consistent: it needs to have rules and needs to follow its own internal logic. Additionally, their needs to be a cost for using magic--there's no such thing as a free lunch. Most importantly, this cost needs to be interesting.
But, what is interesting? To me, the cost of using magic needs to create complications for the character that heighten the tension of the story. One method is to create a cost that forces the character to make tough decisions. The magic system itself could have a distinct flavor, often represented by the limitations, taboos and rituals involved. In some of the best fantasy novels, magic has a distinct personality. It is almost a character in its own rights.
Arguably, D&D has a cost for using magic. Spellcasters are often limited (both in their physical abilities and in the equipment they can use). Spellcasters also have to study/pray. However, I do not consider these costs particularly interesting.
Other games often have some sort of backlash when mages fail their rolls. Sometimes they take damage. Other times the spell has unexpected effects. The first works OK, but it generally isn't great. How often does the damage really have a meaningful impact on the story? The second can work better. Wild magic often has a perverse personality, which--when handled well--can be quite enjoyable. Buffy the Vampire Slayer (both the game and the TV show) capture this perverse personality well. Magic often goes awry, causing more trouble than it solves. Add to this the risk of magical addiction, and you have a very interesting magical system.
Unknown Armies and Sorcerer also have excellent costs. In Unknown Armies, each school of magic has its own unique style and personality. The mages have to perform certain actions to generate power. Both these actions and the resulting effects are highly influenced by the school. For example, a Dispomancer (alcohol based magic) must get drunk to power their magic. their spells typically have mind/perception altering effects. Other schools have their own unique focus--pornography, sleep deprivation, self mutilation, self endangerment, collecting books, and so forth. As you can see, the pursuit of magic can often be self destructive. This system has lots of personality, lots of interesting complications and lots of tough decisions.
Sorcerer takes the self destructive aspect and cranks it up a notch. Here, the characters cannot produce magical effects on their own. Instead, they summon and bind demons. Of course, these demons have their own drives and desires. They will often try to corrupt the character, and (of course) the characters run a constant risk of losing control. As the action in the story heats up, characters will be naturally tempted to lean more and more on the power of their demons. However, while this may save them in the short term, it only increases their risk of losing control.
In play, I've had some trouble with the item and parasite demons, since they often don't have as much personality as their more-animate brethren. The GM also needs to make sure the character's main demon will play an interesting role in the story. I had one player whose demon sounded fine on paper, but it never really came into conflict with the character during the game. Still, if done correctly, it is one of the best magic systems out there.
Ars Magica scores high on my list for historical reasons (it was the magic system that spoiled me for all others) and because of the system's depth. Ars Magica blends spontaneous spells, formulated spells, ritual magic, lab work, summoning, etc. Not to mention excellent heaven, hell and faerie supplements--all guaranteed to win my heart.
To develop a good magic system, you need to know how magic works. I was highly inspired by Frater U.'.D.'.'s essay on the Models of Magic. He's talking about real-world magical belief systems--which is always a good place to start when building any fantasy elements. However, I have modified and extended (and probably abused) his original categories for the purposes of creating interesting stories.
Here the characters get their power from spirits. These could be gods, elementals, ghosts, whatever. Clearly, the most important aspect of spirit magic is the characters' relationship with their spirits. This could be a hierarchical relationship, where one side makes commands and the other obeys. For example, a traditional sorcerer summoning and binding elementals, or a cleric following the commands of their god. On the other hand, it could be a partnership of (more or less) equals--the shaman who offers spirits a sacrifice so they will aid him. Of course, these partnerships are often more one sided than the participants like to admit--and that could be an interesting theme to explore. Other relationships are possible--for example parasitic or symbiotic relationships.
Spirits can also take a wide range of shapes. They can exist only in the caster's mind. They can be ghostlike and ephemeral. They can have physical bodies, appear as shadows, as tattoos on the caster's body, as mystical items (animate or inanimate), as animals, or almost anything else you can imagine.
In either case, the majority of the cost probably comes from the sheer difficulty in managing the spirits. Spirits in stories are usually manipulative and tricky. Many actively deceive their mages. They may portray themselves as more or less powerful then they actually are, commit lies of omission, follow the letter rather than the spirit of an agreement, or simply misrepresent any information they have. Furthermore, characters may accidentally summon the wrong spirit or open a gateway they cannot close.
This is probably the default gaming magic model. Here the character channels mystical energy to make physical changes in the world. In some systems, the mage harnesses their internal energy. In others, they tap external sources of power (magical items, lay lines, midnight, full moons, crystals, etc.). Often energy systems are modeled as hybrids, where the character has a small amount of internal power, but must tap external sources for bigger spells.
This type of magic has a lot of room for variation. Here are a few things to think about:
- Where does the energy come from?
- What does the energy feel like? What does it look like? Taste? Smell?
- What are the costs/side-effects of manipulating this energy
- What happens if you lose control? If you try to tap too much energy?
- Does manipulating this energy leave behind a trace? An identifiable signature?
This represents subtile uses of magic. Here like influences like--pushing the pin into the voodoo doll causes pain in the target. The mage often creates a physical object that represents their desired effects. They can use runes, fetishes, art, whatever. The symbolic representation could be literal or abstract. And the effects are often minor. In many cases, sympathetic magic just seem to give the characters more confidence (represented as a small bonus), and arguably may not be magical at all.
For example, a character may get a tattoo or brand of a fierce creature to improve their fighting ability. Or, they may create a fetish out of feathers that helps them escape from harm (feathers = flight = escape). In some cultures, a band of warriors may demonstrate exceptional bravery while fighting under their banner, but if the banner should fall, their moral crumbles.
Sympathetic magic can be very open ended, and can be combined with almost any of the other magical models. Sympathetic magic often adds a rich texture to the story, but usually has little or no cost (though body modification like branding or piercing is undoubtedly painful). This is OK, since it has little effect on the world.
Here the universe is seen as a gigantic computer. People perform magic by reprogramming this computer. As such, Information Processing magic often has a super science or quantum mechanics element to it. The magic is often tied in with chaos theory, string theory, or whatever.
Here, you need to think about how the universe computer is reprogrammed. Is it something the mage can do mentally? Or does it require special hardware? Does the universe have viruses? Anti-virus/anti-intrusion software? What happens when you program a bug into the Universe? Is there tech support? Sysadmins?
Here, your power comes from your knowledge and your ability to create gadgets on the fly. These items may be magical or technological (think MacGyver). Gadgeteering is very common in the pulp and steam-punk genres. Most gadgets are one use items. You pull them out of a secret compartment in your shoe, or build it from things found under the sink. It has a single effect, then it disappears from the story. Longer term items are better represented by magical/super tech items.
You need to define what kind of gadgets your character can create? Do you brew potions? Do you weave herbs into small charms? Do you build miniature, steam-powered spiders? There are other important questions as well. How long does it take? What tools do they need? How dangerous is it? What could go wrong? But, these questions often need answered on a case-by-case basis.
Here your power comes from the items you cary. These can be magical or super science. Think about the following: How is the item powered? How long do the batteries last? How do you recharge it? Can anyone use the item, or is it keyed to a specific person? Is it mass produced or a prototype? Does it have any design flaws/bugs/curses? How often does the item break down? How much maintenance does it require? Are other people looking for the item (for example, if it is a stolen prototype)?
This isn't really a model of magic, but a modification of other magical models. Many magical systems have behavioral limits. Maybe you need to remain celibate. Maybe you cannot eat fresh meat. Maybe you must perform regular cleansing rituals.
Regardless, these behavior limits can be added to any magic system. However, they shouldn't be added randomly. They should somehow fit into the theme of the magic--they should make logical sense within the magic's rules.
For example, iron and steel might interfere with magic. Here, the mage cannot carry metal on their person (no swords or chainmail). This would be particularly appropriate with a fay-themed magic system, and (most importantly) would have other consequences. Non-mages might use iron shackles to "turn off" a mage's power. Furthermore, someone wearing metal armor or an iron ward would have some protection against magical effects.
Why does the limit exist? What are the effects of breaking the taboo? Are the effects permanent? Do you need to atone? Do they just fade on their own? What are the other implications of these limits? How do they influence society at large?
Tolkien vs C. S. Lewis
One last aspect to consider. I recently read an interesting essay on Tolkien and Lewis. They were contemporaries and apparently Tolkien often criticized Lewis's works, partially because of the religious content (Tolkien was a devoutly religious person himself--he just thought religious writing should be left to the professionals), but also because of the scope.
Tolkien worked hard to create a unified world. Sure, his world had a wide range of elements (elves, dwarves, dragons, etc.), but it drew largely from a single mythical source, and it was woven into a tight, unified whole.
Lewis was a magpie. Inspired by everything from Greek and Roman mythology to Beatrix Potter, he took anything that caught his eye and threw it into Narnia.
Most traditional games are much more Lewisian in scope. I suspect this goes back to AD&D's original "Monster Manual" and "Deities and Demigods" books (and probably even earlier). Both were encyclopedic collections of elements from a wide range of mythological and fictional sources.
A few games--like Pendragon--have taken a more focused approach.
Neither approach is necessarily better than the other. But they will influence the type of story you can tell.
Please Add Your Own
This is far from an exhaustive examination of magical systems, but I think it hits the highlights. Do you have any further models? Any modifications or additional questions we should ask when crafting magic systems? Please leave a comment.