Cinder Wave

A burst of fire billows from your open hands, leaving burning cinders in its wake. Each creature within a 20 foot long by 10 foot wide line in front of you must make a Dexterity saving throw. A creature takes 4d6 fire damage on a failed save, or half as much on a successful one. The fire leaves behind an area of scorching ground that burns for 1 minute. When a creature moves into or within the area created by this spell, it takes 1d6 fire damage for every 5 feet it travels. After 1 minute, the cinders cool and no longer deal damage to creatures walking over the scorched area.

Flammable objects and items not being worn or carried that are within the area of the spell are set on fire.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, you can increase the either the length or width by 5 feet for each level above 2nd. The initial and movement damage increase by 1d6 for every two slot levels above 2nd.