Coven Bolt

A beam of crackling, blue energy lances out toward a creature within range, forming a sustained arc of lightning between you and the target. Make a ranged spell attack against that creature. On a hit, the target takes 1d12 lightning damage, and on each of your turns for the duration, you can use your  bonus action to deal 1d12 lightning damage to the target automatically. The spell ends if you use your bonus action to do anything else. The spell also ends if the target is ever outside the spell’s range or if it has total cover from you. Additionally when someone of your allies within 60 ft. of you also has access to the Coven Bolt spell can use their bonus action to do the secundary damage through the arc. This secundary damage can only be dealt once every round. The original caster of the spell has to maintain concentration on the spell. Everyone who makes use of the arc must be within range of the original spell. 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the initial damage increases by 1d12 for each slot level above 1st.