Crystal Burst

You can only cast this spell on a creature whose hit points have been lowered to at least half their hit point maximum (rounded down) and who you can see within 60 ft. When you cast this spell, multiple crystals burst out from inside the target, causing 1d12 piercing damage as well as severe pain. For the next hour (or until you decide to remove the crystals), the target's movement is halved and they have disadvantage on Dexterity and Strength skill checks, as well as attacks.