Revert the Marksman Update item changes.

That's where the core of the current lethality problem lies.

Every item change since then has had to bear in mind what marksmen are able to do with 4 items granting every possible desired offense stat (aside from penetration): 100% crit, 30% CDR (thank Riot that it's no longer 40%), Waveclear, and stronger dueling/kiting capability plus an open slot for a defense item.

So assassin items can't be too weak, otherwise the ADC's will out-burst the assassin once they have crit. But because assassin items grant AD and are much less expensive--with the intent of early roaming-- almost any champion who builds AD can buy them more efficiently than the alternatives. Which loops into actually becoming the problem a buff to assassin items sought to avoid. Along with that is the fact that it creates a strong anti-armor build long before any tanks can hit their items' power window-- while the many anti-AA armor passives become void and anti-penetration options don't exist.