Chromatic Nova

Clutching a valuable diamond, you send a burst of a damaging element of your choosing outward. Each creature in a 15-foot sphere originating from you must make a Dexterity saving throw. On a failed save, the target takes 8d6 of an element of your choosing (acid, cold, fire, lightning, poison, thunder). On a successful save, the target takes half as much damage.

In addition, all creatures who fail their save are afflicted with a condition depending on the element used. Acid covers the target in a corrosive goo, dealing 2d6 acid damage on the creatures next turn. Cold freezes the target solid until the end of your next turn. Fire sets the target aflame, dealing 1d10 fire damage until an action is taken to put out the fire. Lightning stuns the target until the end of your next turn. Poison causes the poisoned condition for 1 minute. Thunder knocks the target back 15 feet.  

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 level.