You can convert some of your arcane spell energy into a breath weapon.
Prerequisites: Draconic Heritage, sorcerer level 1st.
Benefit: As a standard action, you can convert an arcane spell slot into a breath weapon. The breath weapon is a 30-foot cone (cold or fire) or a 60-foot line (acid or electricity) that deals 2d6 points of damage per level of the spell slot you expended to create the effect. Any creature in the area can make a Reflex save (DC 10 + level of the spell used + your Cha modifier) for half damage. This is a supernatural ability.
Special: If the breath weapon of your draconic forebears does not deal acid, cold, electricity, or fire damage, you choose from among the four energy types mentioned above. See the Draconic Feats table for energy types used by the full array of dragon kinds.
Source: Races of the Dragon, page 102. This version deprecates the one in Complete Arcane, page 77. An additional sentence was added to the end of the Special section for clarity.