The fundamental idea of Athasian magic is to draw up energy from the land in order to fill yourself with power. Thus, the "Raze" spell sequence (Raze I through Raze IX), is the "default form of magic" on Athas. In theory, all other arcane spells are just variations of these core spells; wizards learn to manipulate and channel these plant energies in more specific ways.
This is a companion discussion topic for the original entry at http://www.athas.org/articles/Defiling-and-Preserving