Captain bronza v here, why to build armor pene/ while health protects you from all kinds of damage? When you have 100 armor, how much damage do you take from a 100 ad dmg?
If your 
with 100 armor and 1000 health.
And your opponent
hits you with 100 ad.
How much health do you have left?
Sorry for my bad english, I’m just curious about this to know what to build with tanks
67chrome3 votesWhy to build armor/magic pene , when health protects you from all kinds of damage?
First - because 2 x 2 x 2 is better than 2 + 2 + 2.
LoL is a game where stacking a large assortment of stats rather than focusing on 1 stat is optimal.
HP is effectively multiplied by armor vs. physical damage and magic resistance vs. magical damage. At a certain point, armor and MR are just going to be more cost-effective than HP.
If you have 500 HP, a 500 HP increase is pretty massive - you're doubling your effective health, a 100% increase. Alternatively, a 50 armor increase is only a ~50% increase in your effective hit points (EHP).
If you have 3000 HP, a 500 HP increase is a measly ~17% increase in your EHP. However, that 50 armor is a ~50% increase.
LoL isn't a game about finding 1 good stat and sticking to it: it's about finding a good stat and getting a higher ratio of that stat compared to the other stats available, but still getting the other stats available. As a tank you want armor and MR. So you get armor and MR on them.
Second reason:
flat penetrations are...special.
20 armor penetration vs. a target with exactly 20 armor is going to make you do TRUE DAMAGE! A solid 20% DPS increase at that. 20 armor penetration vs. a target with 200 armor...is not. That's a hair above a ~7% DPS increase.
Vs. early-power items like 
, you can, quite awkwardly and contrary to what the name "armor penetration" and "magic penetration" implies, counter armor penetration or magic penetration harder than they counter your armor or MR.
Some high-end items like 
even predominantly feature flat-penetrations as a major selling point. A handful of champions also have flat penetration skills, so it's a useful trick to know that armor/mr are actually really effective at shutting that down.
It's not like AD or AP see a diminished DPS increase vs. higher health.
Third reason:
everything that's tagged as a "healing effect".
HP/5, jungle camp healing buffs, life steal, spell vamp, self-heals, healing abilities, healing potions, health relics...
If you have 2000 HP and restore 100 HP, you only restore 5% of your maxmium health. If you have 1000 HP with 50% damage reduction and restore 100 HP - you restore 10% of your maximum health. Same effective health in both cases - but the same flat value heal is twice as good and scales even stronger with %damage reductions, where a flat HP increase doesn't improve what healing does at all.
The same can be said vs. hostile life steal/spell vamp. If you have 2000 HP and an opponent hits you with a 100 damage attack with 20% life steal - they restore 20 HP. If you have 1000 HP and 50% damage reduction, they only do 50 damage and only restore 10 HP.
You don't have to be Mundo to appreciate bonus healing, healing is so important for the first jungle clear armor is preferable to health. A large number of tanks and fighters also have some pretty impressive sustain in their kits.
Also taking a dump on 
has it's uses.
When you have 100 armor, how much damage do you take from a 100 ad dmg?
Easiest way to remember how armor and magic resistance scale is this:
100 armor is 1/2 damage taken 200 armor is 1/3 damage taken 300 armor is 1/4 damage taken 400 armor is 1/5 damage taken 500 armor is 1/6 damage taken
Too Ton1 votesI think there is a balance between the defense stats. At a certain point, more armor would be negligible while health would increase the EFFECTIVE health you have. IF you have all health then you'd take like true damage since you have no armor or mr supposedly (you have base but whatever).
thinking man1 votesyou have 950 health after you get hit by a kalista while having 100 armor
100 armor is exactly 50% reduction
armor/mr also prevents things like lifesteal (used to be spellvamp) from working as well as reducing the power of %health damage
Only Play Darius1 votes
JustMyBassCannon1 votesSo here is how it works. Health is the base line for your champion's defense. If you have 2000 HP, then 2000 damage will kill your champion.
If you have 50 Armor, you're taking 66.6% physical damage. This shows up as 33.3% physical resistance.
We can use this to find what is called effective HP, which is a value based on your HP and resistance stats that tells you how much damage it takes to kill your champion.
1000 / ( 100 / ( X + 100) )
1000 / ( 100 / 150 )
...will give you an effective HP of 1500. This means that the champion will die after taking 1500 physical damage.
Unfortunately, I don't have an exact point of where one is stronger than the other. All that I know for sure is that Armor/MR is more efficient for defense before you have 100 of either. That, and if your max HP is double what your Armor/MR * 10, you should buy resistances (ex. if you have 50 Armor/MR and 1000 HP, 50 * 10 = 500, you'll get more effective HP out of Armor/MR than HP.
