Cursed Flame

You start a fire the size of a normal match that glows a sickly green. This fire can not be extinguished by normal means such as water or smothering, the only ways the flames can be extinguished is by letting the fuel burn out or casting dispel magic upon any part of the flame, which dispels any connected cursed flame. The flames act like normal fire otherwise in terms of damage, spread, heat, or any other factor. When cast at higher level the flames burn brighter and hotter, being able to melt through stone at seventh level and magical metals at 8th. Fire Resistance is required to use a torch with 7th level cursed flame and fire immunity is required to do the same  when cast at 8th level