Black Firebolt

You hurl a bolt of blackened flame that emits no heat, only the creeping touch of decay.

Make a ranged spell attack against a creature within range. On a hit, the target takes 4d8 fire damage and 4d8 necrotic damage.

The flames cling unnaturally to the target until the start of your next turn. While these flames persist:

• The affected area appears to smolder with shadowy fire, rapidly decaying flesh, fabric, or material it touches.
• The flames do not spread naturally and do not ignite objects in the usual way.
• A creature can use its action to extinguish the flames on itself or another creature within reach, ending the effect early.

If the flames are not extinguished before the start of your next turn, the target takes an additional 2d8 necrotic damage as the decay deepens.

If this spell reduces a creature to 0 hit points, the affected area crumbles into blackened, ash-like residue.