Tormented Chains

You weave together spectral chains that you can entangle one target you can see within range. The target must succeed a Constitution saving throw or take 4d8 necrotic damages on a failed save or half as much on a save. 

If the target fails the saving throw, it takes half the damage you take as long as you maintain concentration on the spell. The spell ends if you fall unconscious or the target drops to zero. 

You can affect one extra target for every level above 5th the spell is cast at.