A variant take on arcane magic in Dark Sun

Before finding athas.org and all of the wonderful material here, I had been converting Dark Sun to 3.5 rules for a long time. The problem is, I’m not a very good note keeper and tended to save things in little segments, so I’m not sure how much was lost and how much is scattered around in old notes and/or on flash drives. I did just stumble across my old introduction to arcane magic, and considering I basically went in the opposite direction as the Dark Sun Core Rules, I was interested in what people thought of it. Sorry if it is long, but I’m just doing a copy/paste.

Arcane Magic on Athas: Preservers and Defilers

Arcane magic in the Dark Sun setting has the unique feature of being directly powered by life force.  The reckless abuse of magic in the distant past is the primary reason for the harsh conditions found across most of the world in modern times, and this is one of the few historical facts that is common knowledge.  Everyone from isolated, wasteland hermits to the lowliest slaves in any of the city-states, and even the odd, enigmatic Thri-Kreen, are all well aware that “wizards” are responsible for the abominable conditions everything on Athas must endure in the day-to-day struggle to survive.
Among those in the know, there has long been a split among the practitioners of the arcane arts in how best to approach dealing with this effect.  Some prefer to regulate the effect their magic has on their surroundings and do a minimum of damage, while others favor exploiting how empowering life-force can be as arcane fuel and care little for the carnage they leave in their wake.  Those that favor moderation are called “Preservers” and those that care more about their own empowerment are called “Defilers”.
This ideological debate is not widely known by the population of the Burnt World.  The general consensus is usually that all “wizards” are “defilers” and too dangerous to be allowed to live.  Elves tend to be aware of the different approaches, druids certainly know about this (but are still as likely to try and dispose of any arcane caster as they are to figure out what philosophy to which an individual adheres), and the nobility of the city-states and others that have some form of education might be aware of this age-old rift among the practitioners of the arcane arts.
Otherwise, it is mostly an internal affair that only matters to those that use arcane magic.
Contrary to what those that have only heard about preservers and defilers might believe, preservers are not able to power their spells without drawing on life-force.  Their main goal is to be as judicious as possible with their spellcraft, and when they do employ magic they aim to spread the inevitable damage out among as many living things as possible in order to avoid doing irreparable harm to one living thing, or area, in particular.  If done properly, most simply will not notice any obvious damage caused by a single preserver powering his spells.  If gathered together in groups, even the most cautious preservers can do a great deal of damage to the surrounding environment because of the cumulative effect their magic will have.
Likewise, defilers are not likely to be madmen running about turning every plant into spent ash and corrupting the ground into lifeless wasteland.  They are very well aware of where their power comes from, and to recklessly destroy habitable areas is both depriving themselves of a resource they could otherwise rely on for years and risking being discovered by any local intelligent creatures.  For the practitioners of the arcane arts, being discovered is often a guarantee of a painful death.
This leads to the uncomfortable realization that the line between a “Preserver” and a “Defiler” is hardly objective, and preservers are as prone to using “defiling magic” in a time of great need as defilers are to utilize “preserving magic” in a day to day context.  It is more a question of personal ethics and morality, and less a rigid status capable of dividing a playable class into two very different variants.
In other words, preserving and defiling are different approaches to classes with arcane spell features, both capable of doing the same things and both relying on life energy as the power that drives their magic.  One is no greater than the other, but defilers are often seen as more powerful because of their quickness to call upon the full range of their capabilities.
As arcane spell users become more powerful, they can begin to draw life force from more than just plants and the ambient environment.  At first this just involves turning vermin to spent ash but can advance to intelligent creatures, including PCs and NPCs.  Preservers can do this as easily as defilers, but abhor it and would never conscience such actions in all but the most dire of circumstances.  Defilers are only as apt to care about such matters as their alignment dictates.
The “preserver vs defiler” choice must be made by a player when his character first gains arcane spells, as it is a divide in the social setting of the game.  However, the main consequences in terms of rules are often the risk of alignment migrations and some feats being less fitting than others.  Within the game world, there can be a tremendous difference between how a preserver is treated in comparison to a defiler.  Only a small handful of spells, feats, and other content requires a character be specifically a preserver, or specifically a defiler.
A character that is a preserver can become a defiler through “wanton defiling”, which will be used in various places to describe the use of defiling magic when there is less than a dire need.  This is handled in the same fashion as alignment migrations.  A Defiler can become a preserver, but often only through an arduous series of tasks and the casting of an Atonement or equivalent spell by a willing NPC who has judged the character repentant and deserving of forgiveness.
For rules purposes, “defiling magic” refers to metamagic feats, and other features arcane spell casting classes gain in the Dark Sun setting that require a defiling check to be rolled (aside from regaining daily spells).