Item to counter lethality build.
Alright, well the mob has spoken, and lethality hate is the FoTM. People keep suggesting removing lethality from ranges. (seriously?) I think if anything is going to change from this, adding an item that can be built to counter lethality build would be best way to handle the situation.
The way to build against lethality, is to build armor. If you use a true tank support such as Leona, Braum, or Nautilus you won't have as much of an issue, as removing 50 armor from 200 doesn't do much. Now the only issue with this is that ADCs and assassins do not usually have room for an armor item. They have Maw for MR while still gaining AD, but no AD/AR item exists. (Well Ez has iceborn gauntlent, which is the exception where armor is viable.)
So for an offensive armor item I would personally like to see Warlord's Bloodmail unretired with new stats. The passive, while previously weak, is the kind of thing that would fit on ADCs/Assassins, as it rewards aggressively seeking out kills.
Warlord's Bloodmail: 3250 Gold (Pickaxe + Chain Vest + Giant's belt + 575 gold) +30 Attack Damage +400 Health +40 Armor
UNIQUE Passive: Upon champion kill heal 30% health over 2 second. Upon kill assist heal half. Additional kills with 15 seconds grant half.
I think this is really fairly balanced, would work well on ADCs and Assassins, and generally wouldn't be easy to abuse on other champions, as it works off of kills.
It would also be a fun pick for some other champions to. Tryndamere could ult in and heal at the end, Kat would be sweet with it, and I would probably wind up running it and spirit on Trundle.

(typically crit/ad/attack speed set up) for them to pick up an early
early game might actually make them be able to duel and trade with the lethality builds
already run lethality builds so they get that item you suggested and then get
and now they are completely over powered
vs ad in mid. and so on...
cuz they arent buying pots and arent wasting gold on
and the long sword (350g) builds directly into
(which is 1100g) -350g makes it 750g is what they need on 1st back to get ahead vs the scaling armor runes
at 1300 gold and you start
is render nearly useless, for the record, 84.2 is exactly Jinx' lvl 18 armor value, so at lvl 18, someone with full lethality build would be doing true damage to jinx if she had no armor items.
has 800 flat health, if you build this item you increase your durability without spending money on a stat that will be negated,
has 700 health, this is almost 30% of an adc's total HP pool meaning that you are getting the equivalent of 30 armor without allowing your enemy to negate the stat you're investing on
well if you are a lethality champ/build path why would they ever get a
gives you both armor and health, BotRK gives a measly 25 attack damage plus it works based on AS, for ADCS it might work nicely (not for Jhin though) but on assassins building BotRK is a joke :S
and one of
/
.