Bhah'b'h's Solar Rebuke

Radiant light wreathes your body until the spell ends. You emit bright light to 10 feet and dim light for 10 feet beyond that.

Until the spell ends, you have access to a pool of 8d6. If a creature that you can see within range hits you with an attack, as a reaction you may choose as many dice from your pool as you'd like then make a ranged spell attack to cause radiant damage in that amount. 

Whether your attack is successful or not, the number of dice selected are subtracted from the damage pool until it is completely expended, at which point the spell ends.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.