Corwin's Cocktail

You ignite the rag connected to your bottle of rum and throw it to a point you choose within range and which explodes and causes a roaring Rumamist's Fire. Each creature in a 10-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 6d6 fire damage on a failed save, or half as much damage on a successful one.

The fire spreads around corners. It ignites flammable objects in the area that aren't being worn or carried.

Flip a coin.

On heads, for the next three rounds, the Cocktail creates a 10-foot-radius circle of fire, around the original target. Any creature that moves into the circle or starts its turn inside the circle must make a Dexterity saving throw. A creature inside the circle takes 3d6 fire damage on a failed save, or half as much on a successful one.

On tails, the fire disperses leaving no remaining trail.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the initial damage increases by 1d6 for each slot level above 3rd.