Agonizing Movement

Your magic seeps into the muscles of a creature within range. That creature must make a Constitution saving throw. On a failed save, the creature's muscles are wracked with painful shards of arcane energy. If they move on their turn, at the end of their turn they take 1d4 force damage for every 5 feet that they moved. At the end of each of its turns, an affected target can make a Constitution saving throw. If it succeeds, this effect ends for that target.