Whether you are playing an arcane or divine caster, casting spells in Primal Earth may take a toll on your character’s body.
Each time a caster casts a spell, she must succeed a Caster Strain check (Fortitude DC 10 + the spell’s level) or become fatigued for 8 hours. Failing the saving throw while fatigued incurs additional penalties, as written below.
Metamagic feats that increase the spell’s levels do not raise the fortitude DC. The Oracle’s Lame curse immunities do not protect her from gaining negative conditions from failing Caster Strain checks.
The exact effects of failing a Caster Strain check are as follows: Fatigued for 8 hours to exhausted for 1 hour to staggered for 1 round/spell level to unconscious for 1 round/spell level.
Recovering from fatigue or exhaustion requires 8 hours of rest.