Warriors of Destiny
Potion of Fire Breath
(Source: Dungeon Masters Guide, 2nd Edition):
This potion allows the imbiber to spew a tongue of flame any time within one hour of quaffing the liquid. Each potion contains enough liquid for four small draughts. One draught allows the imbiber to breathe a cone of fire 10 feet wide and up to 20 feet long that inflicts 1d10 + 2 points of damage (d10 + 2).
A double draught doubles the range and damage.
If the entire potion is taken at once, the cone is 20 feet wide, up to 80 feet long, and inflicts
5d10 points of damage. Saving throws vs. breath weapon for half damage apply in all cases. If the flame is not expelled before the hour expires, the potion fails, with a 10% chance that the flames erupt in the imbiber’s system, inflicting double damage upon him, with no saving throw allowed.