Holy Fire

6th-level Evocation
Casting Time: 1 action
Range: 90 feet
Components: VS
Duration: Instantaneous

You call upon the Light to incinerate your target with prejudice, creating a bolt of divine energy in your hand and hurling it at the target with unerring accuracy. The target must make a Dexterity saving throw, taking 5d6 fire damage and 5d6 holy damage on a failed save, or half as much damage on a successful one. On a failed save, the target is also starts burning with holy fire, taking 2d6 fire damage and 2d6 holy damage at the beginning of each of his turns. The save to end the burning is equal to your spell save DC.
If the target is an undead creature or a fiend, they have disadvantage on the saving throw and are set ablaze even on a successful saving throw.
At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, both initial and persistent fire and holy damage are each increased by 1d6 for each slot above 6th.

Source: Homebrew