Caustic Poison (3.5e Feat)
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Caustic Poison [Epic, Monstrous]
Your poison can damage creatures typically immune to poison.
Prerequisite: Con 24, Poisonous natural weapon, 20HD, At least one other feat pertaining to poison such as Ability Focus (Poison)
Benefit: Your poison becomes so toxic that it can damage inorganic structures, deteriorate an undead body, or overcome magical defenses. Creatures immune to poison such as Constructs or Undead take half damage from your poison.
Normal: Your poison cannot affect certain enemies.
Special: Poison that deals Con damage against a creature with no Constitution score still has no affect.