Mana Draining

Many of the broken champs out there (Teemo) rely very heavily on their mana in order to make characters broken. A concept my friend and I have bee thinking of is somethin much like an already existing item. Much like how blade of the ruined king takes 6% of an enemy's hp per hit, I think an item called Circlet of the Fallen Queen that has a similar effect with removing some percentage of mana per hit. In order to justify the cost of the item, which should be somewhere in the 3000s, it should come with cool down reduction and health buffs.