Cleave

You unleash a razor-thin wave of invisible energy toward one creature you can see within range.

The target must make a Dexterity saving throw. On a failed save, the target takes 10d6 + 40 slashing damage, or half as much damage on a successful save.

Decapitation. If the target rolls a 1 on the d20 for its saving throw, the attack severs its head, killing it instantly.

A creature is immune to this decapitation if it doesn’t have or need a head, is immune to slashing damage, or cannot reasonably be decapitated due to its anatomy. Such a creature instead takes an additional 10d6 slashing damage.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, its damage increases by 2d6 for each slot level above 6th.