Vicious Breath Feat 17

The intensity of your draconic breath lays waste to the environment and your foes. When you use Dragonkin Breath, the area of your breath becomes difficult terrain for 1 minute. Any creature that enters the area of your dragonkin breath or is occupying your breath's area at the end of its turn takes 4d6 damage of the same type (basic Reflex save against the same DC as your dragonkin breath).