Black Dragon Lineage

(Dragon Magic, page 15, DnD 3.5)

[Draconic]

You have attuned yourself to your black dragon ancestry and can poison foes with your touch.

Prerequisite

Draconic Heritage (black), Sorcerer level 3

Benefit

As a standard action, you can convert an arcane spell slot into a dangerous poison that you deliver by touch. At any time before the end of the same turn in which you activate this ability, you can make a melee touch attack as a swift action. The poison renders the target fatigued and deals 1d8 points of damage per level of the spell slot converted; 10 rounds later, the same effect repeats. Each time, a successful Fortitude save (DC 10 + the spell slot's level + your Cha modifier) negates the fatigue and halves the damage.