Devils Flame

Dark purple flames wreathe one creature you can see within range. The target must make a Dexterity saving throw.  On a failed save, the target burns with dark purple flames for the spell’s duration. The burning target sheds dim light in a 10-foot radius. These magical flames can't be extinguished by nonmagical means. As long as concentration is maintained, the target takes 8d6 fire damage at the start of its round. 

If damage from this spell kills a target, the target is turned to ash.

When cast at level 7 or 9, the damage increases by 8d6 for each two levels higher.