Noxious Breath is a skill located in the Ardent Flame (which can be found in the Dragonknight skill tree). Noxious Breath is a morph of Fiery Breath.
Noxious Breath deals the following types of damage: Poison Damage. Which means that it gets buffed by the following blue champion point trees: Mighty, Piercing, Precise Strikes, Thaumaturge. Also the following red champion point trees protect against this skill: Hardy, Thick Skinned.