4th-level Enchantment

Casting Time: 1 bonus action (which you take immediately after hitting a creature with a Melee weapon or an {@variantrule Unarmed Strike XPHB})

Range: Self

Components: V

Duration: Instantaneous

The target takes an extra 4d6 Psychic damage from the attack, and the target must succeed on a Wisdom saving throw or have the Stunned condition until the end of your next turn.

Using a Higher-Level Spell Slot.

The extra damage increases by 4d6 for each spell slot level above 4.