Abyssal Resistance (3.5e Feat)
From D&D Wiki
 Abyssal Resistance [Abyssal Heritor]
Your ancestral blood makes you tougher against poison and electricity.
Prerequisite: Con 13
Benefit: You gain 2 points of electricity resistance for each Abyssal Heritor feat that you have, and a +1 bonus to fortitude saves against poison. These resistances stack with any racial abilities you may have.
Special: As your body becomes more demonic, it is also weaker against the forces of law. You take an additional 2 points of damage from lawful weapons.