In regular way, Carnage dont proc Avenging Storm : it is not a weapon attack. But there is one weapon that can make an effect (static charge) using abilities that use the weapon as component. Lord Darryn's Voulge cause Static Charge on carnage, and it is a weapon feature. Every enemies in the Carnage area take the stacking effect / lightning damage on crit, even on top a disoriented weapon effect on crit for the Barbarian upgrade. With Avenging Storm, that mean a Lightning Carnage.