Talk:Nasus/@comment-24663301-20140630003448/@comment-15280970-20140719023914

NagaSpawn "I don't actually build any AD on Nasus. I have a rune page that I use for a lot of ADCs which has armour pen reds and quints for a total of 19 (if I recall correctly) armour penetration.

My reasoning for this is that Nasus' main damage source is his Q, and because it technically doesn't really scale with AD, the armour pen will give it better overall damage."

I did build armor pen before following the same idea, however I don't think it is worth it. Armor penetration increases your damage by P/(100+A-P) With P being penetration and A being the enemie's armor.

Take idoneous 54.1 armor vayne at lvl 12. 19 Armor penetration increases your damage by 14% on her. Higher armor targets will make armpen less effective. At 100 Armor you get a 10% increase in damage. 6% at 200. With AD runes you get extra damage on every auto attack. Armor pen is good stacking it with last whisper, but nasus can't allow that on his kit.

We can also factor in nasus E to make armpen more worth, in this case you add a 20 armor reduction (lvl1 E)  on 54.1 Armor (34.1 with debuff) vayne your damage is increased by 16.5%.So, while armor penetration does increase your damage on low armor targets, it does not increase your damage on minions since minions don't have any armor earlier in the game. This hinders both your lifesteal and your last hitting. You also lose a lot of early kill potential since auto attacks always deal more damage with AD.

At the end, AD gives you an easier time earlier in the game with higher sustain, kill potential and farming capabilities. This earlier advantage means you will farm more(More Q stacks), get items sooner (like CDR which means more Q stacks) and may get some kills wich means that you will get items sooner and will be free farming a while and that means... even more Q stacks.

In conclusion, AD reds or AD reds+ Quints are more efficent than armor pen reds or quints on nasus because he will have a better early game, and a better early game means more Q stacks that will outdamage hard that 14% damage increase on armorless targets.