Blade of Nightmares

The next time you hit a creature with a weapon attack before this spell ends, your weapon is weathed in dark energy that freezes your foe in terror. The attack deals an extra 1d6 psychic damage, and if the target is not immune to the frightened condition, its speed is reduced to 0 until the end of its next turn. If the attack was an opportunity attack, the target is also frightened until the end of its next turn.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the extra damage increases by 1d6 for each slot level above 1st.