Chaos Storm

You hurl two spiraling pinpricks of light that collide and explode into a flash storm of chaotic energy.  Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. On a failed save, roll two d8 to determine damage type on a successful save, roll only one d8. For each d8, add 2d6 for the damage type. If you roll the same number on both d8s, the chaotic energy swells. Roll 2d6 for each d8, then roll another d8 for damage type, continuing to add 2d6 until you roll a different damage type.

A creature can only take two different types of damage from this spell,  where each damage type is determined by the number on the d8, as shown below.