Writhing ribbons of quasi-real darkness extend from your hand. As an action, you can make a melee spell attack with the tendrils against any creature within range. On a hit, the target takes 2d8 cold damage and must succeed at a Dexterity saving throw or be restrained.   A creature that starts its turn restrained by the shadow tendrils takes the cold damage again. It can take an action to make a Dexterity check against your spell save DC to free itself.   On your turn, as a bonus action, you can drag a creature restrained by the shadow tendrils up to 15 feet closer to you.   The tendrils have AC 13 and 12 hit points. They are immune to bludgeoning damage and to piercing and slashing damage from nonmagical weapons. They are vulnerable to radiant damage. If the tendrils are destroyed by damage but the spell is still in effect, you can re-form them on your turn as a bonus action.