I read this about 6 times and it still doesn't make a lick of sense.

It makes total sense.

Before you even hit mid game you can one shot minions.

The entire game through you should be attacking enemy champions.

One set of runes do you good the entire game. The other only mildly benefits early game.

What is the purpose of slotting your runes to farm minions when you can farm minions just fine without them?

Building for the weakest things on the map is what doesn't make a lick of sense. Zilean can **** near one shot a minion early game and he's arguably the best farmer. They're your rune pages if you want to waste them on minion be my guest.

Which basically reduces the effectiveness of your flat pen by half.

100 MR - 40 Magic Pen (Flat) = 60 MR.

60 / 2 (void staff/mastery) = 30 MR

vs.

100 MR / 2(void staff/mastery) = 50 MR

50 MR vs 30 MR, you're only getting 20 instead of 40 from your flat pen.


That's what I said, flat pen makes the mastery worse. If you're flat pen is leaving the person with 20 MR, that 15% reduction isn't doing much.

Magic penetration. It's more useful in late game.

But late game you will have a Void Staff, which makes flat MPen not as useful, though still very good. It depends on the champion imo. Any caster-based champion will probably get Sorcerer Shoes, which with MPen reds hits 30 MPen, any extra is wasted. Any spell with 1:1 AP ratios will benefit far more from AP runes because a simple Void Staff will make other available MPen not as good as simply more damage. People like Ryze benefit a lot from MPen because he has pretty bad ratios and getting people to almost no MR will help his burst much more, plus he gets free AP from his ult.

I play annie and ive been working on my own personal build getting bits and peices from others and coming up with my own but im still not 100% comft with it, and its cause of this whole Magic pen. Now i have the 15% talent + magic pen marks, and my question is more directed at my item build. I would get flat cdr glyphs and get a golem buff and that would solve my issues but since i run with a jungler, that isnt possible because i want to get atleast 38% cdr. So my items right now is ionian boots(15%cdr), rod of ages, rylias scepter(forgive my spelling if its off), deathfires grasp(15%cdr), void staff, and death cap. Ive been wondering about 2 things, 1 is do i need sorc boots and should i get haunting guise , or can i make do with a void staff, the other thing is , is it getting a mejai's a viable option since her ap ratio isnt good. And just to point out the deathfire grasp and boots combined with masteries i get 38%cdr even. Just wondering which out weights the other magic pen vs cdr vs ap.

Was hoping some of you could help me out.

It depends entirely on the champ/ability you compare it to.

One thing you want to heavily consider is that Sorcerer's Shoes will give you 20 magic pen. Against many targets who don't itemize MR for a while, that will bring them down to 10. Reducing 10 MR to 0 is actually pretty valuable, so I would actually push you to make an exactly 10 Magic Pen rune page (.95 * 9marks will only give you 8.55, so get 1.45 magic pen from glyphs: 3 magic pen glyphs). This will give you the most damaging spells you can early on, especially since marks aren't good for AP, and glyph flat AP isn't very strong. You'll only sacrifice a small amount of damage late-game (9ap at level 18) turning some glyphs into magic pen.

So does that mean having them reduced to 0 MR, IF they have 30 MR if not more is better than almost reaching cap on cdr? Having tibbers 20 seconds earlier is very nice specially if team fights happen more often or ganks.

Well, the example Phreak provided, that's assuming you take 3 Mpen glyphs and the rest AP, nothing wrong with putting CDRs instead.