I don’t know either, casting speed will effect the animation speed but I’m not sure what else. It’s thrown around a lot that Lightning Tether deals it’s damage 3 times per second but never that the frequency of damage can change so I’m unsure if casting speed is what controls/determines this either.
Also, I wonder if it is both the electrocute damage that scales with cast speed as well as the direct lightning damage? To be honest, it seems unlikely that the electrocute damage would scale with CS. If it doesn’t, that would mean that only 35% of the direct damage scales with CS, which is only a portion of the total damage when you include DOT.
I doubt the Electrocute does scale with casting speed, what would be the point after all if you are just refreshing the same DoT but at a faster rate? 
Furthermore, this would make Allagast’s Arcane Net even more weird: you deal Aether damage that doesn’t scale with CS, Lightning damage that scales with CS, and electrocute damage. It should convert all the damage and/or have other benefits (e.g., +total damage with a longer cooldown).
Wait, what? Why do we have a set partially dedicated to Aether Storm Box if it is so wonky mechanically-speaking :eek: