The addition of lethality in the 2017 season of League of Legends has caused a definite run on Youmuu’s Ghostblades. It’s amazing the shop can even keep them in stock. But what is lethality, and how does it work?
Lethality involves the interaction of armor and armor penetration, stats that have existed for quite a while in League of Legends. In the past, armor penetration has been divided into two categories – flat and percentage. Flat armor penetration simply reduces the target’s armor by the flat amount for that specific attack. Percentage armor penetration acts on a percentage of the target’s total armor, so it scales in effectiveness based on how much armor that champion has purchased.
But lethality, odd as this sounds, is scaling flat armor penetration. For each attack affected by lethality, the target’s armor is reduced by a flat amount, and this amount scales with the target’s level. Armor penetration will not take a target’s armor below 0, but since all champions have base armor that scales with their level (except Thresh), scaling flat armor penetration can be effective even on champions that aren’t spending their gold on bonus armor.
To get a feel for exactly how this effects combat, let’s first take a look at armor. Armor essentially increases the effective health of champions by 1% for each point of armor. For an example, take Nasus, at level 1 with no items. He will have 561 health and 24.9 base armor. This puts his effective health at about 700. That is to say, it will take 700 physical damage to kill him.
So now, let’s say he stupidly heads out to the Rift without buying anything, and encounters a fed Varus who purchased a Serrated Dirk. The Serrated Dirk gives Varus scaling flat armor penetration based on Nasus’ level. Since Nasus is level one, the flat armor penetration is 6.22 (0.6 + 0.4 x target’s level / 18).
This doesn’t effect Nasus’ maximum health, which remains 561, but it does effectively reduce the effect of his base armor to 18.68. Keep in mind this reduction only takes place for Varus’ attacks and skills; Nasus will still have 24.9 base armor against any other champions without lethality or armor penetration.
So because of the Serrated Dirk, Varus only has to deal 666 physical damage to Nasus to kill him, down from the 700 anybody else would have to do. That’s why lethality can be much more effective than previous armor penetration items, like Last Whisper, which only penetrates bonus armor, not base armor, and does so in a percentage. While this would be helpful to take down a Poppy with three Chainmails, it has absolutely no effect on our Nasus.
And since 4 out of 5 enemies in any given match on the rift are typically not building any bonus armor, you can start to see why lethality, via items like Youmuu’s Ghostblade and Edge of Night, is becoming the build of choice for attack damage champions.
legit the only fun I can have as ADC is Ghostblade into Edge of Night. I really really hope Riot doesn’t nerf the build
— Yiliang Peng (@TSMDoublelift) January 31, 2017
We can see the effect further if we scale our Nasus up to level 18, but assume a full AD build with no bonus armor or health. That will give us 2091 health and 84.4 base armor, so 3856 effective health. But that same Varus, even with just that Serrated Dirk, will only have to deal 3647 physical damage.
Of course, why would he just have the Serrated Dirk? If he’s like Doublelift, he’ll be coming at us with at least 35 lethality (20 from Youmuu’s Ghostblade and 15 from Edge of Night), and have to deal 3124 physical damage. So with just the lethality from those two items, our Nasus’ effective health bonus from base armor is almost cut in half, and he’s a tankier champion. Not to mention that those items offer other perks, like attack damage, cooldown reduction, movement speed bonuses, and magic resistance.
If we look instead at a high-priority target, like another ADC, things will get even more interesting. A level 18 Ashe with no bonus health or armor would have their effective health cut from 3349 to 2694, about a 20% reduction in survival potential.
Of course, these are all super simplified examples, and champions typically have a mix of all sorts of bonuses at work in the complex formula that calculates armor and effective health in real time. However, this explanation hopefully demonstrates the potential of lethality. It isn’t totally OP, as the reductions in effective health aren’t massive cuts across the board, but you can easily see how it can help pop squishy targets in a real hurry.