Firewater

By means of the firewater spell, the wizard changes a volume of water to a volatile, flammable substance similar to alcohol and likewise lighter than water. If this substance is exposed to flame, fire, or even a spark, it will burst into flames and burn with a hot fire. The firewater created will evaporate quickly and be useless even if it is securely contained and sealed, so it must be ignited soon after its creation.

Note: This spell originally appeared in this form in Unearthed Arcana for Advanced Dungeons & Dragons (1st edition) from TSR. Its use here is for the purposes of providing context for the campaign only.