Darkfire Web

A web of Darkfire crackles out around you and five streaks of fire rapidly snake along the ground toward up to five enemies that you can see within range, leaping towards their target and exploding into a column of flame upon reaching them. Each target must make a Dexterity saving throw, taking 8d6 fire damage on a failed save, or half as much damage on a successful one.

Alternatively, all five streaks of fire can instead converge toward a single target, dealing 12d6 fire damage on a failed save, or half as much damage on a successful one.

You can only cast in these two configurations. If you want to target multiple enemies, but less than five, the other tendrils trail off and dissipate. 

The fire can travel over obstacles up to 5 feet high, and ignites flammable objects along its path that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for each slot level above 4th.

These flames do not hurt neither the caster's body nor the caster's equipment, except for clothing in the flames' immediate area, but can be used as a heat source like any other fire. However, the flames do not produce any light and were invisible to anyone without darkvision. The last property was why it was sometimes used as signal or beacon for creatures with such vision for it was brighter to darkvision than other fire. To those with darkvision, the flames are black and purple in appearance.