Concentrated Fireball

You attempt to attach a mote of fire to a creature or object within range. Make a ranged spell attack against the target. On a hit, the mote is attached and as a bonus action on every turn for the duration you can cause the mote to explode in a fireball. All those within the 20ft radius must succeed on a dexterity save or take 8d6 fire damage on a failure or half as much on a success.

This spell's damage increases by 2d6 for each spell level above 6th.