Introduced in the preseason patch 6.22 back in November, Lethality was supposed to fix the issue where AD assassins were completely ineffective against tanks. For a long time before Lethality was introduced, AD assassins were in a state where no matter how much Armor Penetration they built, tanks would still shrug it off, while the rest, meaning squishy ADCs and Mid Laners, had to suffer getting snowballed on by the assassin and one shot over and over again for the rest of the game. Lethality was supposed to fix it by giving you some Armor Penetration up front and scaling the rest with levels. Unfortunately, that’s not how it ended up, causing Riot Games to admit the problem and promise to find a fix as fast as possible.
As it is right now, building Lethality items feels underwhelming due to the huge power loss the items used to have when compared to what they are now. This is due to the way Lethality works at present, giving you 40 percent of the Armor Pen you would have got in previous patches and scaling the rest with levels. That made AD Assassins too weak in the lane, all for the promise of a better late game which they got not get to because of the fact that they didn’t do well enough in lane.
That is ignoring the fact that AD Carries, trying to be at least somewhat useful in the early game, started building Armor Penetration items in Season 6. The introduction of Lethality fucked them over even more than AD assassins, to be honest. Now, most Marksmen were left with building Critical Strike Chance, which only becomes good with an Infinity Edge and two Zeal items, like Runaan’s Hurricane or Rapid Firecannon, assuming that they got them before the tanks on the enemy team could stack their Armor to a ridiculous decree.
Okay, the problem is clear. How is Riot planning to fix it? It’s not clear at the moment, however, it’s been said that the devs might actually flip the ration between straight up Armor Penetration and its scaling component. If it is 40% flat and 60% scaling armor penetration now, it would be 60% flat and 40% scaling after the buffs. It’s hard to tell whether it’s enough or not, however, we certainly hope that Riot Games can find the sweet spot. Two entire roles depend on it.