As you guys know, casters are generally AP. For them, the main damage item is Rabaddon's Deathcap: a massive flat boost to AP with a sick passive that increases their AP overall. Thus AP casters are able to deal massive damage with their abilities.
For AD, the Infinity Edge is often called the AD Deathcap. But it's not. It offers a good boost to AD, but the massive price is greatly applied to the increased crit damage.
Thus, AD casters are left with a dilemma. They need damage to make their spells stronger, but their money is wasted on crit, lifesteal, etc. when buying items. I'm sure you all agree that characters like Kha'Zix and Talon are just not as viable because of this.
Therefore there needs to be some sort of flat AD item. Maybe not a massive, 300 AD boost or anything like that, but something flat that would help spells hit harder.
I understand that with an ADC this item would imbalance the game. Therefore I think its effect should be diminished for ranged characters, forcing them to get Bloodthirster or something like that.
I'm not really sure what items it should build out of, or what the price and stats should be, but I'm open to ideas, and it's be great if you guys could help out.