Wizard

Wizards will mechanically not differ much from the way they are set out within the PHB. As arcane casters, though, players must decide whether to walk either the Path of the Preserver or the Path of the Defiler. Unlike choosing a class feature (such as picking a school of magic), a caster doesn't simply ascribe to one path or the other for life - a caster may decide to defile land whenever he casts a spell, just as he may decide to spare the land and choose to preserve it with any given spell cast.

Not everyone may believe that, though, even if it is technically true. To the members of the secretive Veiled Alliance, any wizard who has ever defiled should be considered a Defiler, and the Veiled Alliance is of the opinion that all Defilers should, and must, be executed in due time. The rules for Defiling and Preserving can be found here.

Because arcane magic usage is taboo across Athas, the acquisition of some casting components outside of the easy stuff should be handled in-game. There will undoubtedly be some components that would be impossible to acquire on Athas due to the environmental and historical context of the place - you won't, for example, be able to find any kind of pixie dust because all of the pixies have been extinct for centuries. It should be up to the GM to assign a similar and sensible material as a component for that spell.