Duality Sphere

A thrumming, pearl-sized sphere of energy silently hovers to a space within range and pulses, detonating in a burst of bright light that is subsumed at once by a cosmic darkness. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 3d8 necrotic damage and 3d8 radiant damage on a failed save, or half as much damage on a successful one.