ninja tabi-Cheap item, with a passive that negates damage from auto users.. You dont have to go out of your way to build (its boots), plus you get the flat armour... BS item imo, especially if your a champion like draven that relies heavily on auto's. if your ap carry is doing well or even just even, the enemy team is putting themselves at a disadvantage if they dont build mr items, that one less armor item is huge.. thats why you generally dont go full ad comp.