Entrapping Amethysts

You expel purple crystals from your hand. When they hit a target they embed themselves into the target (doing 4d8 piercing damage) as well as the ground, making the target make a Strength saving throw to break the amethysts and avoid being restrained. 

To break out, the restrained target can use its action to make a Strength check against your spell save DC. On a success, the target escapes and is no longer restrained.