7th-level necromancy
Casting Time: 1 action
Range: 60 feet
Components: V, S, M (a hand full of ashes from a burned tree, mixed with humanoid ashes)
Duration: Instantaneous
You ignite the ashes into a black flame which doesn’t consume oxigen or any material, but the Soul of the Living.
You make a ranged spell attack against a living, sentient (Wisdom>3) creature within range and deal 5d8 + 15 necrotic damage on hit.
A creature hit by this spell must make a dexterity saving throw or be ignited and engulfed in black flames burning the target for 3d8 necrotic damage at the start of its turn.
The creature can repeat its saving throw at the end of its turn, ending the spell on a success.
If this spell reduces a creature to 0 HP the flames consumes their soul making it nearly impossible to resurrect the creature through other means less than a wish or a divine Intervention.
At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the necrotic damage increases by 1d8 for each slot level above 7th.