The Effect of Season 3 Penetration Rune Changes on AD Carries

The Effect of Season 3 Penetration Rune Changes on AD Carries

Before we start today's blog, I'd like to give a shoutout to Forneas for redesigning my blog's images yet again with the new header image you see above as well as a fun new reddit icon; you can find more of his work at  But more importantly, today we are bringing to you new calculations on the effect of attack damage runes versus armor penetration on the latest Season 3 patch.  The most recent patch marks a change in how magic and armor penetration is calculated: flat penetration is now calculated after percent penetration has been factored in instead of the other way around, and flat penetration runes has been nerfed to reflect this change as seen below.

In today's calculations, we're going to use a few basic assumptions about damage calculations.  All basic attacks will be performed by a Graves (so we are using his base damage and AD scaling) that has invested fully into the offensive mastery tree, the relevant masteries being Deadliness (12 AD @ level 18), Weapon Expertise (8% armor penetration), Havoc (2% more damage dealt), Brute Force (+3 AD), and Sunder (5 armor penetration).  Since this post is meant for AD carries in general instead of just Graves, we will be ignoring damage from skills (Q and R).  Additionally, we are assuming that the target dummy does not have any armor or damage modifiers that are commonly found in the defensive tree.  Damage calculated is using normal autoattacks (no critical hits) without any attack/defense modifiers. Runes used for the simulation assume either 15 attack damage or 19.5 armor penetration.

The early game: level 1

During Season 2, there was a small armor range (30 to 60ish armor) where armor penetration was actually stronger than attack damage runes at around 75 damage.  With the changes to the new penetration system, there is no point where armor penetration is superior to bonus attack damage during the early game; however, the difference isn't dramatic enough that you will be outclassed against another AD carry if you own different runes: assuming a generic starting armor value of 30 (at level 1, the range of champion armors can range from about 20 for supports to 35 for bruisers), a champion like Graves should see a difference of about 3 damage per autoattack landed on an enemy champion, or about 5% more damage dealt overall.  Expand the spoiler below to see the difference in damage done at different armor levels.

Reading the graph is easy! (I hope).  The damage for Graves without runes (but with masteries is calculated).  The red and blue lines you see are the additional damage you get from runes (either AD or arpen) per basic autoattack, or damage with runes minus damage dealt without runes.  The vertical purple line is the average armor of enemies at that level without extra armor items.

Verdict: Attack damage wins against armor penetration at the beginning of the game.

Mid game: level 7 with 2x Doran's Blades

After most AD carries have made their first shopping trip, they usually will end up with 2 Doran's Blades representing an extra 20 damage dealt per autoattack.  At level 7 and with these items, the difference between arpen and AD is much less clear-cut than at the beginning of the game.  Most champions have not bought any defense mitigation items by this point in the game, so it should be safe to assume that enemies average around 50 armor at this time considering average armor scaling.

Whereas earlier in the game damage was always better than armor penetration, the two damage sources nearly break even at the average armor level.  Armor penetration is now stronger than attack damage at lower armor targets (AP carries without armor runes, supports, etc.) while attack damage still holds an advantage versus targets at or above the designated average armor level bruisers and other AD carries).

Verdict: With only minor differences in damage output, AD and arpen runes tie each other in damage output.

Mid game: level 13 with 2x Doran's Blade and an Infinity Edge

With a few more levels and an extra +70 damage from buying an Infinity Edge, armor penetration quickly outpaces extra attack damage for total damage output against most standard targets; however, it does see decreasing returns to damage against high armor targets with AD runes giving a greater increase in damage against targets with more than 175 armor.  At this point in the game, its safe to assume that most of the targets you are attacking don't actually have this much armor yet; even if they do, the difference in damage output isn't large enough for the runes to matter a whole lot.  Against average targets, we will see enough of a marginal damage increase for armor penetration runes to take the edge.

Verdict: With enough extra damage, armor penetration wins out against attack damage for most targets.

End game: level 18 with 2x Doran's Blade, Infinity Edge, and a Last Whisper

When AD carries have enough money to buy a Last Whisper, they generally turn into an unstoppable force.  The same occurs when the 35% armor penetration is combined with armor penetration runes: with a Last Whisper, armor penetration becomes superior to attack damage at every single armor value.  Against a target with no bonus armor and average armor scaling, armor penetration runes allow for a double digit increase in damage dealt per autoattack.

Verdict: Armor penetration is superior at the end of the game.

Final Thoughts

To sum of the findings of today: attack damage runes give greater damage output than armor penetration against enemy champions from level 1 through the midgame until the AD carry starts to build endgame items.  After this point, flat armor penetration runes are much more effective when combined with items because they will increase marginal damage output over the enemy by double digits per autoattack.  Keep in mind that the calculations use the base damage for Graves, although most other carries have similar damage scaling.  I haven't completed mathed out the new items and there may be more optimal AD carry builds for the new season, but keep this general rule of thumb in mind: the more bonus damage you have, the more effective armor penetration is.  

While in the last season attack damage was the clear choice for AD carries (unless you intended to dunk the enemy bot lane at level 2), the new runes introduces a choice for players.  Picking bonus AD now makes you stronger in the early game at the cost of late game effectiveness.  On the other hand, many games are often decided in the first 15 minutes of the game when armor penetration is still ineffective.  Only experimentation with both sets of runes will find the optimal choice for your playstyle.  Which type of rune do you think will be most effective for your personal playstyle?  Early game attack damage, or late game armor penetration? Thanks for reading, and please comment below with your thoughts!

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