Briarhand Smite

You touch a creature (often yourself), wreathing its hands or antlers in spectral brambles. The next time the target hits with an unarmed strike or natural weapon attack before the spell ends, the attack deals an extra 2d6 piercing damage, and the target of the attack must succeed on a Strength saving throw or have its speed reduced by 10 feet until the start of your next turn as briars snag at its limbs.