Blightning

You create a bolt of crackling necromantic energy that arcs toward a target of your choice that you can see within range. Three bolts then leap from that target to as many as three other targets, each of which must be within 30 feet of the first target. A target can be a creature or an object and can be targeted by only one of the bolts.

A target must make a Constitution saving throw. The target takes 5d8 lightning damage and 5d8 Necrotic damage on a failed save, or half as much damage on a successful one. If the target fails the saving throw, its hit point maximum is also reduced for 1 hour by an amount equal to the necrotic damage it took.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, one additional bolt leaps from the first target to another target for each slot level above 7th.