Avowed Dragonfoe

Heroic Tier
Prerequisite: Dragonborn
Benefit: You gain a +1 bonus to attack rolls against dragons. While you are bloodied, this bonus increases to +2.
    Also, when you score a critical hit on a dragon with a melee or close attack, you gain temporary hit points equal to the dragon’s level.

Published in Forgotten Realms Player's Guide, page(s) 132.