AP vs Magic Pen - Which one is better ?

Just after ending the video i get recommended a video from Makkro with the title ''525 MAGIC RESIST'' XD.

Exactly exactly exactly. So glad someone explained quite well some of the basic ideas of penetrations! Even without damage calc formulas and other math things anyone can see this video and actually understand building a bit better on mages and assassins, which i see very often people (even pros) completely trolling it. Great as always very underrated channel

after 10 years of play, i saw the dragon head on the Needlessly Large Rod

Also having high ap scalings favours raw ap more vs high base damage where pen is often more optimal

But is it better to build a lot of ap or magic resist against tanky enemies? Is there a difference in building when enemy has a lot of resistances like a ksante with jak sho or a lot of hp like a cho gath with heart steal? Is it better to stack ap against hp heavy enemies and better to go Magic Pen against high MR enemies?

it's really down to team comp and how much AP ratios your abilities have. Rumble for example can also spike heavily on death cap since his Q AP scaling is 110% but shadow flame just happens to be cheaper and can help with last hitting.

aren't vlads first 2 items normally protobelt and shadowflame? at least last i played they were

you forgot to add that the ratio of base damage vs scaling also matters, which is the reason why syndra is one of the best mages to build pen, her base damage compared to her scalings is one of the highest in the game, especially in the mid game where the first spikes come into play

Hmm intresting i always tought that the math for pen was (BaseMR-flat)* (1-%pen) Nice to see that its the other way around. But also: The more mr the enemy has the less effective flat pen is after more than 150 15pen gives you only 10% more damage where as going from 300 to 360 ap gives you a 20% boost overall (Usually )

Me: *Sees average win rate items from sites* A mathematically correct AP singed doesn't necessarily have a higher average win rate. A mathematically correct Garen shows you should build crit items and one Black cleaver but win rate sites, doesn't even have crit items aside from the occasionally one crit item.(often that anti heal item)

Why is % and flat magic pen works better together? Resistances have a linear scaling so making enemy go from 200 to 190 is the same as 10 to 0

A lot of these "do more damage" champs cant' build MPen items (also the whole category of "do more damage" champs is a vague: every champ wants to deal more damage, but they won't build full damage because they offer something more valuable than raw damage). If you go Shadowflame/Void second on syndra you are going to be much weaker than a syndra that goes Rabadon's second. This is because every point of AP you buy after completing Rab will give you 40% more ap, effectively making all of your AP purchases 40% more efficient. So you begin ramping up beyond the natural curve of AP that champions without Rabadon's have, because Rab straight up gives you 40% more AP. It's like being able to farm 3 imaginary minions for free every wave that you don't need to cs or interact with (this is further enhanced by Gathering Wind/Absolute Focus which is why scaling mages will choose to go First Strike + abs/gathering secondary). Often mages will be in a 3 item slump as they can't acrew gold at the same rate as other champions in the side lane after completing their 2nd core item, and this leaves them effectively stuck at 2 core items until 30~ minutes at which point they could have 3 core items. This issue is most prevalent on burst mages. If you go any Pen item second you are never reaching Rabadons before the game ends, and if you do so happen to get rabadons later in the game at 30 minutes, the fate of the game is pretty much already decided by then. So the real descion of what item to buy when comes after completing, or even during the completion of the first core item, ludens/liandry etc... If you go Shadowflame 2nd, you are saying that the stats you get from buildilng this item and whatever base you get from trying to buy alternator/NLR WILL win you game over just NLR + elixir/darkseal/amp tome/stopwatch, whereas the Rab 2nd player is saying that the difference in ap between 2x NLR and 1xNLR alternator will not change the state of the game, or will only do so in such a small % of games, it is not worth effetivelly maiming yourself for the next 5 to 8 minutes, at which a more important fight could break out.

Is it better to build plated steel caps against Rumble? Cause I think that the 12% damage reduction from its passive is more beneficial than building mr because rumble reduces it anyway.

What do you actually do to deal with tanky champions though? Magic pen literally feels like I am wasting so much gold on a mage in the hopes of dealing with enemy MR, but you still just do absolutely nothing to them. Why does AD pen work so much better?

Reminder that % armor penetration is applied AFTER flat armor penetration, which makes it, in fact,very inefficient.