Level 6 Necromancy (Sorcerer, Warlock, Wizard)

Casting Time: Action
Range: 150 feet
Components: V, S, M (the powder of a crushed black pearl worth 500+ GP)
Duration: Instantaneous

Negative energy ripples out in a 60-foot-radius Sphere from a point you choose within range. Each creature in that area makes a Constitution saving throw, taking 8d8 Necrotic damage on a failed save or half as much damage on a successful one.

Using a Higher-Level Spell Slot. The damage increases by 2d8 for each spell slot level above 6.