Arcane Tether

You launch an arcane bolt of energy towards a creature within range.  You make a ranged spell attack against the creature.  On a hit, the target takes 2d6 force damage and a tether of arcane power attaches to the target.  If the target does not move more than 30 feet away from you by the end of its next turn, it becomes stunned until the end of its next turn, and the tether ends.