Eldritch Lightning

A launch multiple lightning bolts towards up to 5 targets in a 25 foot Cone in a direction you choose. Each creature in the Cone makes a Constitution saving throw, taking 4d8  Lightning damage and 4d8 Necrotic damage on a failed save or half as much damage on a successful one. On a failed save, a creature's hit point maximum is decreased by the same amount as the necrotic damage it took.This reduction lasts for 1 hour or until the affected creature is the target of a Lesser restoration or greater restoration spell.

Using a Higher-Level Spell Slot. You may target an additional creature for each spell slot level above 5.