Clockwork Bolt

You imbue an arrow or crossbow bolt with clockwork magic just as you fire it at your target; spinning blades materialize on the missile after it strikes to further mutilate your enemy.

As part of the action used to cast this spell, you make a ranged weapon attack with a bow or a crossbow against one creature in range. If the attack hits, the missile embeds in the target and causes regular damage. Unless the target (or an ally of it within 5 feet) uses an action to remove the projectile (which deals no additional damage), the target takes an additional 1d8 slashing damage at the start of its next turn from spinning blades that briefly sprout from the missile's shaft. Afterward, the projectile reverts to normal.

This spells additional damage increases when you reach higher levels. You can add an extra 1d8 damage on reaching 5th level (2d8), 11th level (3d8), and 17th level (4d8).