The next time you attack a creature with a melee weapon before the end of your turn, your weapon is crackle with deadly energy. You gain a bonus to your weapon attack roll equal to your spellcasting ability modifier.

On a hit, the attack deals an extra 5d6 necrotic damage to the target to the target. If this attack leaves the target with 20 hit points or less, the target is immediately reduced to 0 hit points. The necrotic damage of this spell ignores damage resistances and damage immunities if the target is a humanoid or undead creature.

At Higher Levels. When you cast this spell using a spell slot of 6th level or higher, the necrotic damage increases by 1d6 and the hit point threshold for reducing the target to 0 hit points is increases by 10 for each slot above 5th.