Cat o’ Nine Tails

Lashing red strands of force erupt from your outstretched fingertips. Creatures of your choice that you can see in a 15-foot cone must make a Strength saving throw. On a failed saving throw, a creature takes 3d6 force damage and can’t move further away from you except through teleportation. On a success, it suffers half damage and no further effect.
As an action, a creature that failed the initial saving throw can make a Strength saving throw, ending the effect on a success. The effect also ends on a creature if you move more than 30 feet away from it on your turn.
On each of your turns for the duration, you can use your bonus action to deal 1d6 force damage to each creature that is still affected by the spell.

At Higher Levels: When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d6 for each slot level above 2nd.