Avrus' Asperous Anklet

As a reaction, when a creature you can see moves within 30 feet of you, you hinder their movement by summoning a spectral spiked anklet, bear trap, or some other movement hindering device. The creature must make a Dexterity saving throw. On a failure, they take 1d6 force damage and have their speed reduced by 5x the level this spell was cated at. On a success, they take half damage.