I miss when ADCs needed to build AD items to deal damage
I've noticed this trend lately, where ADCs don't even build big ADC items early any more, they simply rush attack speed or penetration items.
Nearly every game, I see ADCs building 
as their first item, or 
and 
, or sometimes 
.
They might build a 
first, but they almost never aim to build one of the big three items early any more:
Back in previous seasons, ADCs did no damage without AD. AS was useful as a later multiplier stat, for being able to last-hit a little easier, and for Vayne, but most ADCs couldn't really do much damage with AS alone.
It took me a while to realise why this was happening - it's because of Fervor of Battle. More attack speed lets ADCs apply the stacks faster and build up damage, giving them effectively a free by level 7.
With all that free damage, suddenly building AD doesn't seem that useful - instead, ADCs rush attack speed to apply the free damage faster and armour penetration to make each point have more value.
The keystones in general have really been warping champion balance for the entire season.
