Poison Expert( Complete Scoundrel, p. 80)
Your skill at crafting and delivering toxins has made you a more deadly poisoner.
Craft (poisonmaking) 4 ranks, Poison use,
Poison Master (CS) ,
Choose a type of poison (contact, ingested, inhaled, or injury). The DC to resist both the initial and secondary damage of poisons of this type that you create and use increases by 1.
This feat has no effect on poisons used by other creatures, even if you craft those poisons. It also has no effect on natural poisons (those exuded from a creature's body).
You can gain this feat multiple times. Its effect does not stack. Each time you take the feat, it applies to a new type of poison.