AP/level vs Mpen

First Riot Post

naotasan

Senior Member

Quote:
Originally Posted by ricklessabandon
it's actually very strong.

tbh, the biggest problem with penetration is that it's misunderstood, not that it's underpowered.
Got a place or reference so we can see how mpen works?

For example, using a skill with 10mpen and 10% mpen

ricklessabandon

qa analyst

Quote:
Originally Posted by naotasan
Got a place or reference so we can see how mpen works?
i can (and probably should) write up a clear explanation, but in the meantime i'll quote a post i wrote when someone asked the following:
"Ricklessabandon, how would I caluculate, at any given point, the benefit of getting a haunting guise?"

Quote:
Originally Posted by ricklessabandon
it's simple! (just kidding, it's not.)

follow these quick and easy steps:
1. take your target's current magic resistance (this value would be after all modifiers like buffs and magic resist reduction).
2. apply your magic penetration to the value in step 1 by first subtracting your flat magic penetration, and then removing a portion equal to your magic penetration % value. (e.g., if your target has 55 magic resist and you have 29 | 10% penetration then you would do: [ (55 - 29) * 0.9 ]
3. take the value from step 2 (we'll call it 'x' within this step) and run it through this formula: [ 100 / ( 100 + x ) ]

the result of step 3 is the damage modifier that is applied to your raw damage (like, base damages + bonus damage from ap ratios, masteries, etc) to determine how much damage your target will take. for example, if your target has 20 magic resistance after penetration is factored, then your damage modifier would be 0.8333 and therefore your target would only take about 83% of the damage you're throwing at them.

so, now to find out how effective a haunting guise would be we need more steps.
WE'VE ONLY JUST BEGUN.

4. take your champion's raw damage and modify it by the damage modifier you got from step 3. this is your 'before haunting guise' value.
5. run through steps 2 and 3 again, but this time with 20 more magic penetration.
6. take your champion's raw damage (making sure to add in an additional 25 ability power) and modify it by the damage modifier you got from step 5. this is your 'after haunting guise' value.

the value in step 6 is how damage haunting guise is adding. this number on its own doesn't mean a whole lot, so we need to compare it to something meaningful. the most practical comparisons are to either void staff (70 ability power and 40% magic penetration) or pure ability power.

void staff comparison:
7(a). run through steps 2 and 3 again, but this time with 40% more magic penetration. note that %-based penetration stacks multiplicatively, so (for example) 10% + 40% would equal 46% and not 50%.
8(a). take your champion's raw damage (making sure to add in an additional 70 ability power) and modify it by the damage modifier you got from step 7(a). this is your 'after void staff' value.
9(a). compare your 'after haunting guise' and 'after void staff' values to get the difference in damage for a particular target. btw, void staff costs 810g more than haunting guise so take that into consideration if it's relevant.

ability power comparison:
7(b). take your champion's combined ability power ratios for whatever 'combo' you want to compare. for example, if i wanted to compare damage output for veigar's standard gatling of: baleful strike + dark matter + primordial burst, i would use the value 2.8 (which i got from 0.6 + 1.0 + 1.2).
8(b). modify the ratio from step 7(b) by the value you got from step 3.
9(b). take the damage total you got from step 6, subtract the damage total you got from step 4, and then divide the difference by the ratio you got from step 8(b). this is the amount of ability power you would need to match the damage increase of a haunting guise.

~~ a wild example appears! ~~

i'm playing veigar. i'm level 18 and i have 21/0/9 masteries, flat ap quints, scaling ap seals + glyphs, magic penetration marks, two doran's rings, sorc shoes, deathcap, wota, and 100 ability power from last hitting with baleful strike. this gives me:

-a base damage of 1080 on my 'baleful strike + dark matter + primordial burst' gatling.
-a combined ap ratio of 2.8 for my gatling.
-a total of 582 ability power.
-a total of 28.5 | 10% magic penetration.

graves is on the enemy team and is my primary target since he's a tanky dps burst-mage assassin carry. he's also level 18, and hasn't built any magic resist. that means he has 30 magic resist outside of combat, but 60 magic resist while in combat thanks to his passive. i want to know how good a haunting guise would be considering that i want to deal the most damage i can to graves while his passive is up. since a void staff isn't quite justified in this case, i'll only do the comparison to pure ability power stacking.

1. 60
2. 28.35
3. ~0.78
4. [ 1080 + ( 582 * 2.8 ) ] * 0.78 = ~2113
5. ~0.91
6. [ 1080 + ( 615 * 2.8 ) ] * 0.91 = ~2550 (note: the 25 ap from guise is modified by the ap increases from deathcap and masteries)
7. 2.8
8. ~2.2
9. ~198

from our example we can see that against this graves we would need about 147 ability power to match the damage increase a haunting guise would give. note that it's only 147 ap since it would get boosted to ~198 thanks to the ap boost from deathcap and masteries. so, yeah...haunting guise can be pretty strong but it's really hard to gauge that since the numbers in your ability tooltips don't change and the math behind it isn't something that you'll dive into while in a game.

(apologies in advance for any typos/errors. it's a wall of text so i assume they exist...)
i know that doesn't answer 'how does m.pen work?' so much as it gives an example of it being really effective, but the 'how' isn't something i've tried explaining nearly as much as i've given examples in arguments for/against something--i'd need to make sure that any explanation i write out is clear and helpful. the last thing i want to do is further misunderstanding by not phrasing something properly. i certainly want to write more on the subject though.

Senior Member

holy **** that seems ridiculously complex. does Riot have any plans to re-work mPen, I hope?

daves3hd

Senior Member

The thing with mp over armor pen is that. armor pen can get below 0 and mp caps at 0 ( most of the times you won't get below 0 anyway). But meaning that armor pen can amplify it's damage while magic pen is capped at "true" damage

Talith PA

Senior Member

Why wasn't the magic pen portion of the double penetration quints buffed?

basod

Senior Member

Quote:
Originally Posted by ricklessabandon
tbh, the biggest problem with penetration is that it's misunderstood, not that it's underpowered.
Is there no way to show players visually the difference gained ingame? Some people aren't good at maths you see.

caydi

Member

Quote:
Originally Posted by daves3hd
The thing with mp over armor pen is that. armor pen can get below 0 and mp caps at 0 ( most of the times you won't get below 0 anyway). But meaning that armor pen can amplify it's damage while magic pen is capped at "true" damage
This is just false.

Armor penetration, nor magic penetration, can reduce a target below 0 armor / magic resistance.

But, armor reduction and magic resist reduction can.

The way it works is:

1] Percentage reduction & flat reduction are calculated first, depending on the order they are applied

ie. Trundle with Black Cleaver, uses Agony first: % reduction happens, then attacks and reduces target armor (possibly below 0)

Or

Trundle attacks first, then uses Agony: Target armor is reduced, then whatever is leftover is subject to % reduction (ie, likely won't reduce below 0)

2] Flat penetration is calculated second (ie sorc shoes and marks)

3] Percentage penetration is calculated last (ie. void staff)

The simplest way to think of mpen / armor pen is to think that the largest damage increase you'll see from them is a 1% per point basis.

ie. Adding 20 magic pen (when you have 0), versus a target with exactly 20magic resist will increase your total damage by +20%.

When the target has more than what you have, that number decreases.

If your target has 100 MR (after other penetration is calculated), reduce the effectiveness by about 50%

ie. Haunting guise's 20 magic pen increases your total damage by about 11%

These numbers are incredibly simplified, but that's how you can roughly calculate it.

If you compare that with AP, when a target has 50 MR and you have 30 mpen,
and assuming your skill does 280 damage with a .7 AP ratio

At 0 AP:

Adding haunting guise gives: 297.5 damage
Needlessly large rod: 280 damage

At 200:

Haunting guise: 420 damage
Needlessly large rod: 397 damage

If your target now has 130 MR:

At 0 AP:

Haunting guise: 165
Needlessly large rod: 168

At 200 AP

Haunting guise: 243 damage
Needlessly large rod: 238 damage

tl;dr
The only thing you really need to know is, magic pen and armor pen are very efficient. Buy them if your target has more resistance than you have penetration. There's no reason to rework mpen. It's not terribly complicated.

Xhyros

Senior Member

Quote:
Originally Posted by basod
Is there no way to show players visually the difference gained ingame? Some people aren't good at maths you see.
No. The difference gained is different against every target, unless they all have the same magic resist.

Psi21

Senior Member

The weakness is that we are talking about collecting Magic Penetration essentially in runes slots and 6 items slots.

AP Casters are responsible for the following AP, CDR, M.Pen, HP, MR and Armor

Side Note: (To a small degree AD casters take hits in the various stats they need to collect but it plays helpful when you have at least 2 AD items that offer AD, CDR and Armor Pen., and AS.)
(Where as AP Casters don't have any item that offers AP, CDR and M.Pen.)

But getting back on topic.
As a AP caster you could try to knock a players MR to nearly 0 using the 3 items (A.Scepter, Haunting Guise and Sorc. Shoes). But then you lose 3 items slots. What is worse is the M.Pen you receive from those 3 items can essentially be shut down by a single item (say the, Quicksilver Sash) that cost less than the cost of a Haunting Guise.

But whats worse is that if you want to take it one step further you could instead get the Odyn's Veil which would give the needed MR, +10% reductions in damage and provide a nuke to the defensive player.

Now there is all kinds of things you could argue saying in 3 item slots you could get the needed Armor, CDR, HP and MR you need. That you could additionally figure in M.Pen runes. Or get these same awesome defensive items.

But, trying to become what Tankie DPS has already achieved in the remaining 3 items slots is just silly.
Because meanwhile either Tankie DPS is getting that much more armor/MR or is just relying on say a single items that constantly provides static damage procs like the Trinity Force. All the While these Tankie DPS players are benefiting a standard build of say... 10% reduction in melee damage (T.boots), 10% reduction in Magic damage plus nuke (Odyn's Veil), 20%+ reduction in attack speed with Rand. and/or Frozen heart, (Anti CC) Q.Sash, (Top Tenacity) Merc Treads and 180+ AR/MR.

You see Defensive Items are just too good in this game. The game tends to reward those that play it safe (this was also written up by a review of the game recently.)
If this game is in fact built with DOTA in mind. DOTA had champs with huge bursts of damage.

So how can an AP Caster combat this 180+ MR and 10% reduction in Magic damage? Don't stack M. Pen.

It is actually better to just get a DFG, Massive amounts of AP and multipliers (such as AP per level runes + D.cap) and a void staff.

More AP feeds to your ability deterioration, You gain and extra nuke that can some times receive 10%+ more damage based on the health of your opponent, You get some CDR which you don't get from the M.Pen items and you get a manageable if not equivalent amount reducing your targets MR.

Sure your only saving one item slot (which you probably will put to another type of boots either I.boots or M.Treads) but those item slots are extremely important to a AP caster that doesn't always have an absorb shield or an ability that gives them life return.

Side Note: (I really wish absorb shields abilities only received the champs base MR/Armor and not the MR/Armor of the champion's items.)

TLDR: Lots of rambling that if you can follow have some points.
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