Combustion

You summon a wave of flame that sweeps outward, igniting everything in its path. Unattended flammable objects within 5 feet of you take 1d4 Fire damage and start burning with magical fire, as do other creatures unless they succeed at a Dexterity save. A magically burning target takes an additional 1d4 Fire damage at the end of each of its turns.

Although the fire is magical, it can be extinguished much like mundane flame. As an action, a creature can extinguish the fire on themselves by going prone and rolling on the ground. The fire also goes out if it is doused, submerged, or suffocated.

Cantrip Upgrade. The initial spell damage and the burning damage both increase by 1d4 when you reach 5th level (2d4 and 2d4), 11th level (3d4 and 3d4), and 17th level (4d4 and 4d4).