I thought this might help you out.

Preserving magic does not drain from the surrounding living matter because preservers carefully replace the energy they siphon with their spells; defiling magic creates a blackened radius around the caster.

Using arcane magic is illegal in most of Athas. This is because the reckless use of arcane magic during ancient wars defiled the land. Defiling gives away that someone is using arcane magic.

Arcane spellcasters who devote themselves to defiling receive additional benefits. A character who defiles for all of their spells in a given day receives an extra Action Point at the beginning of the day and an additional extra Action Point at every milestone. If the defiler uses any preserving magic, they must immediately remove an Action Point and no longer get extra action points for dedicated defiling until after an extended rest. This may put them at negative Action Points.

In order to use preserver magics, characters must purchase the Preserver feat. This allows the character to disguise their magic.

Characters may wish to disguise their casting as something other than Arcane magic when they are being observed by someone who is trained in Arcana. Doing so normally requires a Bluff check.