Why Magic Destroys Perfectly Good Games
"Magic" in a gaming system is defined as a sort of black box device which is implemented for story purposes, with little or no logical explanation as to why it’s there or how it works. It’s been taken for granted in the overtired fantasy milieu that there is this force called "magic" that allows weird things to happen for no reason, but it also exists in other environments. In cyberpunk we have nanites that can make laser beams shoot out of someone’s ass. In spacefaring campaigns there are transporter devices and beam weapons that somehow track accurately at distances of 12 light years, and ship drives that allow FTL travel with crackpot explanations. Psionics are another popular form of magic in RPG settings, where psis go beyond seeing whether the card has a picture of a star or a box to perform feats like unpowered flight and making Green Lantern-type energy manifestations.
In any form, the inclusion of magic into a game system invariably breaks all sense of balance. This is because any black box device by definition has no real-world analogue, or even a well-thought out theoretical basis, and is thus devoid of any observational data for the hapless designer wishing to implement it. All he has are some ideas he can steal from other writers who also lacked hard data, combined with some crap he might pull out of thin air. Therefore, the effects of magic are limited to whatever arbitrary values the designer wishes to assign to various effects, within the constraints of practical technology if the game is computer-based. Because game content designers tend to be largely incapable of approaching realistic balance even within the arena of hand weaponry, it comes as no surprise that any magic system that appears is rife with game-destroying balance errors from day one.
This problem, like almost every problem related to RPG design, becomes exponentially greater in the realm of the MMORPG. Any error on the side of weakness in magic will be publically and loudly addressed over the web and NNTP, while any error on the side of overpowering advantage will be exploited to hell and back by the ruthless client until (and if) the problem is "fixed" with a patch, followed by more whining.
Another problem is the way that magic is approached by a typical RPG designer. Having resigned himself to the idea that magic just makes things happen for no good reason, he cannot stop himself from turning magic into an all-inclusive overwhelming technological advantage. Magic becomes air superiority, rifled barrels, and force fields, all in one package. Small wonder then that almost every character in any MMORPG is considered gimped unless he is a mage to some extent.
The only solution for this is constant vigilance and hardcore balancing. It also helps if your basic game design and mechanics are modeled around a no-magic environment, so you can at least get that part right before you try to balance in a magic system. Remember that magic wasn’t included in the original Dungeons and Dragons until Eldritch Wizardry. This was the correct approach. The ensuing generic and boring magic system was a result of a lack of imagination, not a flaw in the overall design process.