The Stars' Fury

A glowing orb is released from your hand, and floats up into the sky. The sky then darkens in 200 feet in all directions, showing stars. The orb then begins to pull light from the stars, and grow larger, until it is fifty feet across. the orb will then explode, shooting rays of light in all directions, striking every creature of chaotic evil within 200 feet. These creatures must make a dexterity saving throw, and on  a failed save take 15d10 radiant damage, or 1/3 that on a successful throw.