Cedric's Afterburner

You throw a small ball of flame at a creature within range. Roll a ranged spell attack. On a successful hit, a creature takes 2d6 fire damage, and becomes surrounded by small motes of flame until the beginning of your next turn. The next time the creature takes damage from an attack or spell before the beginning of your next turn, it takes an additional 2d6 fire damage, as the motes of flame violently burst.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the secondary damage increases by 1d6 for each slot level above 2nd.