I did some math to find out which AP items were the best if you wanted as much damage as possible. I only did the math for Void staff, Horizon Focus, Shadowflame and Rabadon (considering you already have Luden and sorcerer boots).
In the end Horizon Focus is always higher if you can proc its effect. So I’m wondering why every Lux player for example aren’t buying it second item.
That answer is very simple.
Because people are stupid.
And that’s true from Iron to Challenger.
Horizon, Cosmic and Shadow are basicly the same Item in 3 different Flavors.
Yet Shadow has like 7x the pickrate.
AKA, people don’t think, just buy. Just like with Skins. =P