Burning Dash

You rush forward, leaving a flaming trail in your wake. When you cast this spell and as an action on subsequent turns for up to a minute, you can charge in a straight line up to 30 feet. This movement cannot cross gaps such as a canyon and follows the terrain of the path. Any creature in the path of this movement must make a Dexterity saving throw or take 3d6 Bludgeoning damage and be knocked prone, only taking half as much damage on a success and not being knocked prone. The line you travel is ignited as you dash, and stays aflame until the start of your next turn. Any creature that starts its turn in the line of fire or enters the fire for the first time takes 4d4 Fire damage.

You can move normally after using this dash, but only the movement that is part of the dash causes the flame trail.

At Higher Level. When you cast this spell using a spell slot of 4th level or higher, the damage of the fire trail is increased by 1d4 for each spell slot above 3rd.