Voltaic Shackles

You connect a surge of electricity between you and a single target. Make a melee spell attack against the target. On a hit, the target takes 1d6 lightning damage and is magically tethered to the caster. On each subsequent turn, you may use a bonus action to send a jolt of electricity to the tethered target within 5ft and deal an additional 1d4 lightning damage. this effect ends if you do not use your bonus action this way.

This spell's initial damage is increased by 1d6 at 5th level (2d6), 11th level (3d6), and 17th level (4d6).