You have made a special study of dragons and are adept at pulling off deliberate attacks that take advantage of a dragon’s weak spots.
Prerequisites: Int 13, Dragonfoe, base attack bonus +6.
Benefit: You may use a full-round action to make a single attack (melee or ranged) against a dragon with a +4 bonus on the attack roll. Such an attack deals an extra 2d6 points of damage if it hits. For a ranged attack, the dragon must be within 30 feet to gain the bonus to hit and the extra damage.
Special: The bonus on the attack roll and the extra damage stack with the benefits provided by a weapon with the bane (dragons) property.
In the case of a critical hit, the extra damage dice aren’t multiplied.
Source: Draconomicon, page 105.