Potent Poison (3.5e Feat)
From D&D Wiki
Potent Poison [Monstrous]
Your poison attack deals more damage.
Prerequisite: Poison attack, Con 13, BAB +5
Benefit: Choose one of the creature’s poisonous attacks. The initial and secondary damage for this poison increases by one step: 1d2, 1d3, 1d4, 1d6, 1d8, 2d6, 3d6, 4d6, 6d6, 8d6, 12d6. If the attack deals 1d10 points of damage it increases as follows: 1d10, 2d8, 3d8, 4d8, 6d8, 8d8, 12d8.
Special: This feat may be taken multiple times, but each time it applies to a different poisonous attack.