You are connected to one of the elemental planes. Select one elemental plane: air, earth, fire, or water. Whenever you cast a spell with a descriptor matching that plane, add your tier to your caster level for that spell. You gain resistance 10 against an energy type associated with your chosen plane—electricity for air, acid for earth, fire for fire, and cold for water. At 6th tier, this resistance increases to 20. At 9th tier, this resistance increases to 30.
