Tempest breath, also known as Mestil's acid breath was a spell of the conjuration school used by some sorcerers, particularly dragon sorcerers. When a sorcerer cast tempest breath he or she exhaled a green mist of acidic vapors that burned and disoriented any creatures within a nearby zone 15 ft (4.6 m) in diameter. Creatures affected by tempest breath were prevented, for a moment, from taking advantage of their enemies' weaknesses, so disoriented were they by the spell. Dragon sorcerers who used tempest breath were able to, in addition, conceal themselves from sight for a moment through use of the remaining mist. The spell was not particularly easy to cast, it required a few minutes of rest to be recharged.
Before the Spellplague, tempest breath was more commonly known as Mestil's acid breath and was used by both sorcerers and wizards. The area of effect was a cone emanating from the caster's mouth for a distance of at least 30 ft (9.1 m). Like many spells of its time, it grew in power as its caster did, and could only be cast as often as the sorcerer had energy left for spellcasting or a wizard had prepared for it. After the Spellplague, no such restrictions remained.