Fiery Breath is a skill located in the Ardent Flame (which can be found in the Dragonknight skill tree). Fiery Breath is a base skill, and can be morphed into Noxious Breath or Engulfing Flames.
Fiery Breath deals the following types of damage: Flame Damage. Which means that it gets buffed by the following blue champion point trees: Elemental Expert, Elf Born, Spell Erosion, Thaumaturge. Also the following red champion point trees protect against this skill: Elemental Defender, Thick Skinned.