Kings of Dust and Bone
Defiling and Preserving
Arcane spellcasters on Athas must draw upon the vital life-essence of nearby creatures and vegetation to power their spells. (This only applies to arcane spells; see “The Weave of Magic” sidebar, PHB page 205.) The act of destroying life through such spellcasting is called defiling, and those who do it are called defilers. Arcane spellcasters who internalize the cost, fueling spells with their own life essence, are called preservers.
Each time an arcane spell is cast, any nearby vegetation withers and turns to ash, rendering the ground infertile for decades. A radius of ashen ground extends from the caster, 5 feet for every level of the spell cast. A cantrip leaves only a pair of ashen footprints. Living creatures within the affected area lose hit points equal to one-third of the spell slot’s level, rounded down. The caster herself is unaffected.
An arcane caster can, with some effort, choose to cast spells by preserving instead of defiling. There is no external destruction caused by preserving. Instead, the caster suffers 1 hp of damage per spell level, which cannot be avoided or reduced. Each cantrip inflicts 1 hp of damage on the user, but only the first time it is cast in a fight; multiple uses of the same cantrip do not cost more than 1 hp.
The effects and implications of defiling and preserving are enormous. But to the average Athasian, there is no difference; all arcane spellcasters are deemed evil and dangerous, the reason the burning world is a desolate wasteland. (And they sometimes have difficulty discerning arcane spells from divine or psionic effects.) All city states have laws criminalizing arcane magic.