Developed by a particularly heinous necromancer who enjoyed scarring his enemies, netherflame fireball creates a bead of sickly violet flames that streaks out to a point you choose within range before exploding. Each creature in a 20-foot radius takes 4d6 fire damage and 4d6 necrotic damage, or half that damage with a successful Dexterity saving throw. Furthermore, the damage from this spell causes particularly deep burns that cannot be healed by natural healing or rest. Only magical healing allows a creature to recover from the damage inflicted by this spell.