PSA: Armor is still really great this season.

I made this post in a thread about how people build bad tank builds and then complain that tanks can't itemize defensively against carries because of the armor pen build. I decided to use some math to show how armor stacking is still incredibly effective against ADCs! for the purposes of these calculations I removed both the armor pen from masteries/runes AND the armor from masteries/runes (since these things can be variable) - this is PURELY to show how armor and arpen interact with each other as you build additional armor items. Volibear is used because he was specifically the example (someone said "tank voli dies too fast" with a build listed as this: )

---

Let's do some math real quick. If an ADC is utilizing the "armor pen build" (let's say they have ) That's 30 flat Arpen and 45% bonus armor pen. We're giving them some crit too since most carries finish out their builds with it these days, even if they are going lots of arpen!

Volibear has 85 base armor at level 18. Meaning that with no armor, he has 55 effective armor against the above build (since no bonus armor is shred, since no armor items). This gives him 33% less damage taken from physical attacks, roughly. So a 1000 damage auto attack will do 670 damage to Volibear, roughly. Great.

With one armor item (let's say the Dead Man's Plate from above), he has +50 armor, giving him 130 armor total. First, we take 45% from his bonus armor (we'll say 25 armor because of laziness), leaving him with roughly 100 armor. This is further reduced by flat pen to 70 armor. With 1 armor item, we take 41% reduced damage from the physical attack. Extra 8% reduction, seems kinda worth especially over time (that's like 80 damage an auto, adds up pretty quick).

Let's add Randuin's. So we add 60 bonus armor to the equation giving us 110 bonus armor. This leaves us with roughly 60 bonus armor after % pen, 30 bonus armor after flat pen, meaning we have roughly 110 armor. At 110 armor, you take 52% reduced damage from physical attacks, a full 11% more reduction for a single armor item! This means in our 1k crit scenario we're taking almost 200 less damage compared to no armor items an AA, and this is before including Randuin's crit reduction.

tl;dr: Making a single additional armor item on top of Dead Man's Plate (as long as it gives at least 60 armor) will reduce 200~300 damage an auto attack from a marksman, even if they're utilizing an "armor pen" build.