Ember Blade

You choose a creature you can see within range and attempt to ignite it in flames. That creature must succeed on a Constitution saving throw. On a failed save, the creature immediately takes 1d4 fire damage, and takes another 1d4 fire damage at the end of its next turn.

This spell's initial and secondary damage increases by 1d4 each when you reach 5th level (2d4), 11th level (3d4), and 17th level (4d4).