This sounds kinda like a cloudkill spell, doesn't it?A great wyrm is capable of breathing out a cloud of poisonous gas four times a day; such a cloud is 60 yards long, 30 yards wide and 26 yards high, and all who are caught within it must save vs. breath weapon or suffer the poison’s effects. Victims who breathe the fumes will be immediately incapacitated by choking and nausea, collapsing at once without defending themselves or attacking in any way. The victims will then die in 1-4 rounds. Saving against the breath weapon will reduce the victim to half of his former hit points (round fractions up) and will leave him choking and gasping; he will, however, be able to attack at -2 “to hit” odds, and can defend himself, though without armor class bonuses for dexterity. These latter effects will last 4-16 rounds.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.