Conduit

You reach out to a target and electricity comes up out of the ground and courses over it. The target must make a Constitution savings throw. If they succeed, a random area within 5 feet takes 1d8 lightning damage as it discharges out of the target. If they fail, any creature that enters or starts its turn within 20 feet of the target takes 6d4 lightning damage at the start of your next turn, as the build up causes the target to become a conduit for your destructive energy. The target takes 3d4 lightning damage for each creature that takes damage.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher: the damage increases by 2d4 for creatures, 1d4 for the target, and lasts 1 more round for each slot level above 3rd.