### New Armor Pen Calculations @ Red Response

Akdar

Senior Member

So... what's the thought behind the new armor calculations? I thought it was supposed to be a good thing.

Old way = (Armor - Armor Pen) - % Pen
New way = (Armor - % Pen) - Armor Pen

GREAT! If they left the numbers the way they were. But now changing them it's worse.

Let's say the typical is Sorc Shoes and Void Staff. The Old Equation was (MR-20)*.6 The New Equation is .65MR-15.

Running the numbers (easy with excel if you don't want to use math and set the equations equal to each other). You'll See:

Target's Magic Resist = Old Way's Actual MR / New Way's Actual MR
1MR = -11.4 Old Way / -14.35 New Way (So -3MR in favor of new way)
30MR = 6MR Old Way / 4.5MR New Way (So -1.5MR in favor of new way)
60MR = 24 / 24 So Pretty much anyone mid game is even old way / new way.
200MR = 108 Old Way / 115 New Way

I'm just curious what the changes were supposed to achieve.

Soiyeruda

Senior Member

The equation is more efficient although I'll admit it was silly and pointless if they weren't going to leave the numbers the same.

Obliv

Senior Member

It's more intuitive. Now, % and flat penetration stack with positive interference, like they originally did. They used to negatively interfere with each other. Also, you won't get down to negative MR/Armor with penetration. Only reduction can do that, and it is applied before penetration. Stacking many penetration items is now more powerful, but just getting one is a little bit weaker.

By the way, anybody buying a void staff would have taken the archaic knowledge mastery, so your functions are incorrect, albeit only slightly.

o(x) = (x-20) * 0.6 * 0.9 = 0.54x - 10.8
n(x) = 0.65 * 0.92 * x - 15 = 0.598x - 15
n(x) < o(x) for integral x <= 72.

CooLTanG

Master Recruiter

do the math for armor pen, it took like a 20% hit on Runes alone!

Orbital Nuke

Senior Member

Yes, but the benefit stacks positively now. So in cases where champions come with extra penetration built in (like darius!) then this will make them even better.

In your specific cases, the numbers are close, I would guess that with runes, it would push them slightly over, ie use the talent, one 35% item, one flat item, and 9 greater marks of penetration and then come back.