Exhaled Barrier

 
Prerequisite(s): Half Dragon, Breath Weapon
 
Benefit: You can choose to have your Breath weapon create a 10'x10' vertical plane of energy, rather than it's normal effect. The wall lasts for 1d4 rounds. Any creature passing through it takes the normal damage for your breath weapon. If you create the wall where creatures are, they all take damage as if they were passing through it. A successful Ref sv vs DC=10 + 1/2 your HD + your Con Modifier, halves this damage. If your breath weapon does not normally deal damage, the wall instead deals 2d6 fire damage.
 
Source: Races of the Dragon