Can someone provide concrete examples of when to build armor vs health?

Question

I read this excellent explanation of how building armor provides diminishing returns in terms of reducing damage, but scales effective health linearly. I am bad at math. So in what cases would you need to stay alive longer and prefer to build armor as opposed to wanting to increase your health? And how does increasing your health scale your effective health?

I'm not sure if I'm asking the right questions, so any help is appreciated.

Edit:

To clarify, I'd like an example matchup and build with reasons why you might choose armor or health based on flat stats. I guess I need an explanation of the math. If building armor scales effective health linearly, is it the same as just building health?

Thanks for all the helpful responses. This makes a lot more sense to me in words than numbers. I'll vote on one after I go through these.

Answer 1

Now the great thing about armor: It's cheap and it increases your effective Life.

The bad thing? Effective life is pretty useless if you have no flat HP. Also it won't protect you from Magic/True Damage.

Health

Now let's take a look at the obvious things first: You should build HP(/MR) instead of armor if you are up against an opponent that mainly deals true or magical damage. Flat HP is also a great option on champions that already have a percentage damage reduction or Armor/MR Built In (Leona/Alistar). There are also a few champions where abilities scale with HP, so buying some extra armor on these is a good thing.

Armor

Of course it's a good idea to build armor against AD heavy teams but Building armor on champions that scale well with it (Rammus/Taric/Malphite) is also pretty safe. Now generally you want to stop building HP after you reach 3000-3500 Health and focus on Armor MR since The Effective HP you get per armor point after this cap is really incredible (about 3 times as gold efficient as buying normal HP).

Generally it's the best to build a mix of both HP and resistances, and not focus on one thing. But if you are laning against an AD heavy opponent (Riven, Lee Sin) an early chainmail can safe your life sometimes.

Answer 2

(I use the term DR to mean damage reduction, whether it be armour or MR.)

DR is effectively a multiplier to your health. Therefore, it's more valuable the more health you have. Against the relevant damage type, bonus DR is worth more than an equivalent amount of bonus health if you have more than 100 health and zero DR.

But there are ways around DR. Having high armour is useless against true damage or magic damage. This might tempt you to stack HP instead, but that only leaves you vulnerable to percentage damage (such as from Nasus's ult).

The simple conclusion is that a mix of decent HP and decent DR benefits you more than focusing excessively on either would.

So beyond this general case, look out for these situations that prefer one thing or the other:

• Champs like Rammus whose abilities scale with health, armour, or MR. They should obviously focus on building the relevant stat.
• Champs with flat (as opposed to percentile) healing abilities, including lifesteal. DR devalues enemy damage without devaluing flat healing, whereas HP devalues both damage and healing.
• Enemies with percentile APen (Last Whisper)/MPen (Void Staff). These increase the effectiveness of flat APen/MPen.
• Enemy team comps that pretty much deal only one type of damage. (I've seen this happen. Troubling.)
• Enemies who deal true damage. Stack HP.

Answer 3

If the enemy's damage is HP%-based ( Vayne, Mundo, Elise, Vi, Gnar ), then it is risky to build items with purely high HP increase ( such as Warmog and Frozen Mallet ) though Omen and Sunfire can still be considerable.

Randuin decreases attack speed which could be useful for AA with HP%-based damage (usually Carry with BotRK) while Sunfire's health increase is lower than Mallet and Warmog, has decent amount of addtional armor and the dps from passive is not that bad.

However, if the enemy's damage scales with AD, it goes in two ways : the ones with spell and the AA.

For spell dependent ( such as Zed, Pantheon, Talon ), building HP with armor is necessary. Purely armor items can get less useful if their with armor penetration, but pure HP will shorten your tankiness in teamfights. So if they go through more armor pent, put more HP but maintain armor.

For AA though, ( such as Caitlyn, Jinx, Yi ) armor can be your priority with a little less worry on HP. With Randuin's + Thornmail, them having IE/BT is not a great threat, considering that your champion is built to be a tank and has isn't relying on 9 mastery points on defensive tree. Put more armor but maintain HP.

Answer 4

The big advantage health has over armor is the additional effective health against magic damage. Health scales with both Armor and MR. The more Armor and MR you have the more effective each point of health gets.

On some champions you prefer heal over resistances because they have %-damage reduction. Maokais ultimate reduces incoming damage by 20%. Building health on him is way more effective than resistances. Another example is Wukong. He gets free Resistances from his passive thus making health more useful.

Building Armor against Health depends on the matchup. Against a Vayne health stacking is bad. Go with Armor and AS slows. Factoring in a decent enemy team composition I would always prefer Health over Armor because you have the additional defense against magic damage.