Deep Breath is a skill located in the Draconic Power (which can be found in the Dragonknight skill tree). Deep Breath is a morph of
Inhale.
Deep Breath deals the following types of damage: Flame Damage, Magic Damage. Which means that it gets buffed by the following blue champion point trees: Blessed, Elemental Expert, Elf Born, Master at Arms, Quick Recovery, Spell Erosion. Also the following red champion point trees protect against this skill: Elemental Defender, Iron Clad.
ESO Skillbook