Gameplay ITEM CONCEPT ---We want Balance Right!?

So how about creating another new item that has attack speed slow like "Warden's Mail" and magic resist! We have Frozen Heart and Randuin's Omen for the AD champs but nothing to counter the AP champ's like Kayle, Azir, and so forth that use Nashor's tooth...unless you buy Frozen Heart/Randuin's and Banshee's/Spirit Visage :( two parts to counter one=not balanced.