Armor/Magic Resist worth all the money?

[quote=Kuribohlv9]hello there. i recently read HeAt's Game Mechanics: Vol. 1 where i learned the formula for ar/mr i was bored and did some calculations and found out this. (this could be found by just holding over armor in-game but i found it trough math) 50 ar/mr = 33% reduction 100 ar/mr = 50% reduction 200 ar/mr = 63% reduction 300 ar/mr = 75% reduction the percentage is how much less damage you will take. as you can see when you get more and more ar/mr the growth effectiveness decreases. that means that reduction per ar/mr gets lower the more you buy. with that in mind do you really want 300 ar for 75% reduction? isn't it more worth to just get 200 or even 100 ar and more health or AD/AP/Supportive items? at some point, it will no longer be (money) worth getting more ar/mr. at one point you should start buy health or stuff with passives that can assist you better. this mean planning stuff more carefully to not get too much ar/mr will save you alot of money. this also means that offensive items that grant a little ar/mr stat will give a nice boost to survivability. ideas?[/quote]

[quote=Jebus McAzn]At a certain point, flat health probably does overtake armor/magic resist in terms of usefulness per gold spent. However, against any good team, you'll be facing a balance of magic and physical damage, and will want to evenly increase both your armor and magic resist. After getting the typical tank set (Sunfire Cape, Banshee's Veil, Force of Nature, Randuin's Omen, Mercury's Treads, Guardian Angel) with some minor variations, possibly (Thornmail, Wriggle's Lantern, Quicksilver Sash, Hexdrinker), you reach at most 250 in both armor and magic resist, and that's assuming you're really fed. The point is, against most good teams, you'll never run into the issue of buying more armor/MR not being worth it. Sure, against an all physical-damage team, it's fun to get 300 armor and then stack Warmog's, but in any ranked game, you will never, ever have this problem.[/quote]

[quote=Kuribohlv9]the question to ask then is: do you really need 250 ar/mr? the reduction per ar/mr gets high priced after 150 ar/mr. getting 200 to counter their arPen and MPen but after that you should go for items that support yourself or your team rather than more ar/mr.[/quote]

[quote=Kael312]i think the idea is that thats what most people do, its not terribly difficult to hit 175 armor/mr, and after that i usually get something thats got health[/quote]

[quote=caucheka]i've hit 800 armor on rammus. enemy team was all physical dps and i was taking like... 10% of their damage.[/quote]

[quote=DEWO]You have to still consider flat and % based Ar/Mr reductions. That is why tanks stack it anyway.[/quote]

[quote=Azzurite]Actually every point of Armor/Magic Resist increases your effective HP equally, no matter how much you have of it. Consider a player with 1000 health. Let's say he has 100 armor, resulting in a 50% reduction in damage taken. Every attack deals only 50% damage to that player, so you need to deal 2000 damage to kill him (2000 * 0,5 = 1000) which is a 1000 health increase in effective HP. Now say we give him 300 Armor, resulting in a 75% reduction in damage taken. Every attack deals only 25% damage to that player, so you need to deal 4000 damage to kill him (4000 * 0,25 = 1000) which is a 3000 health increase in effective HP. So having 300 armor is exactly triple the benefit of having 100 armor, which means both net you the same relative benefit, with no effectiveness decrease at all. Seeing this, every point of armor gives you 1% more effective health. So for example, let's compare a thornmail to a fully stacked Warmogs Armor and their effect on effective health against physical attacks. A thornmail gives you 100% more health. A Warmogs Armor gives you 1220 health. So when you have more than 1220 health, a thornmail will add more to your surivability against physical attacks than a Warmogs Armor, since 1221+100%=2442 which is greater than 1221+1220=2441. Obviously a Warmogs also increases your effective HP against Magical Attacks. I will not go into the cost/benefit analysis here. Just throwing it out :)[/quote]

[quote=Kuribohlv9]thank you for that answer. it was exactly what i was looking for when creating this thread. i hadn't considered the total HP effectiveness of Ar/Mr. more HP grants more Ar HP but more Ar grants more % of your HP that adds to your Ar HP.[/quote]

[quote=Jebus McAzn]But the actual question is concerned more with the cost effectiveness of buying more AR/MR. Consider a champion with 300 armor and 3,000 health. He takes 75% reduced damage from physical attacks, effectively quadrupling his health to 12,000 vs pure physical damage. Now let's say he buys a Thornmail. It costs 2000 gold and gives him 100 armor, so he now takes 80% reduced damage. This effectively quintuples his health to 15,000. From 2000 gold, he gains an effective 3,000 health, or 1.5 health per gold. Now let's say he gets a Warmog's Armor instead of Thornmail, and let's assume he fully stacks it. His base health is increased by 1370, so he now has 4,370 health. His 300 armor is still effectively quadrupling that, making it 17,480 health instead. This investment of 3000 gold gives him 5,480 health, or 1.83 health per gold. Disregarding the other effects, you see that flat health pays off only at very high amounts of armor/magic resist, generally above 250 or 275. Basically, buying armor/magic resist is good until around then - there's no need to stack anything up to 400 unless you're playing Rammus against an all-physical team or Galio against an all-magical team.[/quote]

[quote=Visfarix]You should probably also consider that some champions deal [b]true damage[/b] and your AR/MR will not block any of that damage. What happens when you only stacked a bunch of Ar/MR, only have 2000 HP, and an Olaf or Cho'gath is running at you about to [[Reckless Swing]]/[[Feast]] you for 17%/40% of your HP in one hit?[/quote]