System Wank - Magic

Oh, this is a tough one.  There are a lot of great magic systems out there.  And by "magic" I'm going to include any special effects system such as psionics or The Force.  Because, ultimately, they are essentially the same thing.

Given the breadth and variety, I'm going to go with one winner and two honorable mentions.

Honorable Mention I - Unknown Armies

Unknown Armies is a strange and twisted urban fantasy setting and system.  If you've never looked at it, I highly recommend it.  It is wrong in all the best ways, and the system supports the wrongness extremely well.  For all that, I'm not sure I could ever play it.  I just don't think I'm wrong enough for it.

There are two kinds of magic users in Unknown Armies, and both kinds of magic are powered by obsession.  Avatars are obsessed with embodying one of the archetypes of human existence.  My honorable mention, though, goes to Adepts, and the concept of charges.

Adepts gain power by paying homage to an obsession.  They think that some aspect of this world holds the key to ultimate power.  Only by delving into that aspect to a degree that no mere mortal can match can the Adept channel that power.

Each time the Adept does something to feed his obsession, he gains a minor charge.  If he does something that is the pinnacle of his obsession, he gains a major charge.  Creating magical effects then requires him to spend those charges.  Additionally, each obsession carries a set of taboos.  If the Adept breaks a taboo, he loses all his stored charges.

The awesome thing about this is that Adepts are forced to act in accordance with their obsession in order to gain power.  You can't claim to gain power from an obsession with TV and then only pay it lip service.  You have to watch the TV.  All the TV.  And hunt down the stars of your shows.  And collect the props from your shows.  And go to conventions based on your shows.  If you want power, you have to become the creepiest super-fan ever.  Because the rules say so.

(As an aside, I've always wanted to port UA's charges into D&D to power the cleric's "turn undead" ability.  Do your daily worship, you get the minimum amount.  Perform a major deed, get a major charge.  Break a taboo, lose all the charges.)

Honorable Mention II - RIFTS

OK, I'll let you pick up your jaw off the floor.  Yes, really, I happen to like the magic system in RIFTS.  While the basic nature of PPE is just a straightforward spell point system married to a D&D-style spell list, the extensions of it manage to really make it shine.  (As a note, I stress system because the list of spells, especially in the original book, is terrible.  The cutting and pasting is blatantly obvious, and the power of the spells is all over the map.  Like most of RIFTS, the attention of a good editor could make all the difference.)

So, for a basic spell, you look at how many PPE the spell costs, and subtract that from your personal PPE.  Quick, easy, simple.

If you happen to be on a ley line or nexus, you can draw on the PPE of the location to fuel the spell instead of your personal reserves.  This helps to explain why certain locations constantly draw the attention of mystic and religious groups.

The PPE available in the ley lines rises and falls in certain rhythms.  You see peaks at full moons and the solstices and equinoxes.  Mages are therefore inclined to keep an eye on the heavens and time their rituals carefully.

You can pool the PPE from several casters, or even draw PPE from non-casters if they are willing.  Ta da, you have a reason to start a coven or cult.

There is an option to store PPE in an item.  Now you have mages decked out in staffs, shrunken heads, crystals, and gris gris bags.

When you kill someone, you can harvest the rush of PPE that pours out of them.  In fact, it's double the normal amount the person has.  If the person is pre-pubescent (i.e., a "virgin"), the number is higher.  A babe is higher yet.  Hence, you have reasons for ritual sacrifices, including sacrificing virgins and infants.

Since a number of the higher-level spells have PPE requirements that are well above the daily allotment for any wizard, casters are practically forced into performing rituals.  And, due to the ways you can access additional PPE, those rituals are best performed when in line with genre tropes.  So simple, and yet so evocative.

Winner - Shadowforce Archer (Spycraft)

Again with the jaw on the floor?  Yeah, I picked Spycraft (specifically in the Shadowforce Archer setting material) as having the best magic.  But, oddly enough, not the actual magic system (which is very flavorful, but kind of flawed).  Instead, I love the psionics system.

Spycraft is a d20 system.  But, instead of bolting on a largely incompatible system of memorizing spells the way D&D did (for legacy reasons), it dug deep and used the heck out of the d20 structure to fuel its psionics.

First, to be a psion, you have to take one of the three psion classes.  Physical adepts are able to control their own bodies.  Mentalists are super-smart and can control energies with their minds.  Telepaths are, well, telepaths.  Each type of psion has three branches of study, represented by feat chains.  The base feat for each branch unlocks the ability to take ranks in the psion skills of that branch.  Using a psion ability involves a skill check.

So, suppose you want to play a physical adept.  The three branches are Sensory (you are able to extend your senses to a crazy degree), Adrenal (you can become faster, stronger, and more resistant to damage), and Psychometabolic (you can channel your psion energy to heal yourself, reshape your body, or even resist aging).  At first level, you pick Sensory Basics.  This gives you access to a bunch of skills like Danger Sense (activating it allows you to avoid being surprised and dodge blows) and Structural Awareness (you can touch a wall and feel where weaknesses and openings are in it).  You assign your skill points to them just like any other skill.

This means that a psion has to invest a considerable amount of character currency into being a psion.  It keeps the psions on an even level with soldiers and facemen.  They are equally powerful, psions are just more flashy and capable of things beyond human.  For the most part, psions and non-psions are pretty well balanced at every level.

When a psion wants to use a power, he picks a skill and makes a check, using the standard skill check mechanics.  For some checks, you consult a table that cross-references the check result with the character's psion level (generally the level in the psion class, similar to D&D's caster level) to give a bonus amount.  For others, you can interpret the result of the check directly to determine things like duration or area of effect.  It's just that simple.

The limiting factor on psion powers is that each use costs vitality.  (Spycraft uses the vitality/wound system instead of hit points.)  Thus, using a lot of powers tends to fatigue the psion.  At the extreme end, psions can end up with severe headaches and nosebleeds from using their abilities too much.  (In my campaign this is referred to in-setting as "body burn".)  This has three very nice balancing factors.  First, it means that psions almost always need high scores in every ability, or at least to avoid low scores, as a high Constitution is needed for high vitality.  Second, it makes for a very simple way to track how often the powers can be used without introducing another number onto the character sheet.  Finally, the more a psion draws on his powers, the more vulnerable he becomes to a simple punch or bullet.

The whole system is very elegant, incredibly extensible, and powerfully leverages all the strengths of the d20 system.  The psion classes provide additional class abilities that reinforce their own stereotypes.  There are additional psion feats that allow the psion to focus on one or another skill and make it incredible.  I won't say that this is the best possible system (especially as I worked out a few ways to improve it when I was building my d20 Rifts conversion), but it is the standard by which I measure all other systems.