Magic Madness (3.5e Campaign Option)
From D&D Wiki
Types of Madness
Any character that has cast a spell has a chance of gaining magical madness. When a person casts a spell he rolls a will save with DC 0 + Two Times Spell Level + Spell levels of every spell previously cast, else gain a type of madness. The type of Madness may be determined in any way.
The world is segregated, not many study the Arcane arts but those that do are focused.
Religion plays a major role in this setting, the churches may claim that the arcane is the work of evil (or good if the church is primarily evil) or they say that it is a curse for not following their deity well enough.
Notes on psionic/magic transparency
- Elans have madness from birth.