Kassadin Thunderlords 2 hit proc

Picked up Kassadin after a long hiatus due to me not feeling skilled enough to use this champion. Played a few games and began noticing that I could proc Thunderlords with just an auto attack and then activating Nether Blade immediately after the attack connects. Seems the spell damage is being counted as a seperate damage source and not bound to the auto attack. Leads to some super brain dead trades with melee mid laners. Video included was just me trying to obtain video proof in an intro game.