Source: Races of Faerûn
You have studied centuries of Calishite lore regarding geniekind.
Benefit: Choose one type of energy: acid, cold, electricity, or fire. You add +1 to the DC of saving throws for any sorcerer spells with the energy type descriptor that you cast. This benefit stacks with the Spell Focus feat if the spell you cast is from your chosen school.
Special: You can gain this feat multiple times. Each time you take the feat, it applies to a new energy type.