Graves VS ninja tabbi

Question of clarity here, anybody have a clue how Nina Tabbi interact with Graves new AA?

Does the passive read each part of the scater as one attack with bonus damage per exra shot, or will it see each projectial as a separate AA and reduce the damage of each one separate?

And for that matter how does randuins omin work into this with how graves crits? Because I believe that instead of more damage he gets more projectials only, but still randuins will reduce the damage. And again, How does this item register the projectials? All as one attack, or each separate?

Depending on how this works can mean Graves will really struggle against some footwear.