The Importance of Armor
This Summer, the metagame was quite unusual. With the rise of the Disco Pony, aka 
Leshrac, we saw a metagame centered around magic and pure damage, despite 
Glimmer Cape being introduced this year. 
Storm Spirit, 
Lina and 
Queen of Pain were quite dominant throughout that phase.
Now however, we have a new patch and a new meta on our hands. 
Alchemist has gained an increasing amount of popularity, as the meta swings back to a more physical DPS based one. Guest-writer GorgonTheWondercow talks us through Armor, one key mechanic in the game when it comes to understanding physical damage.
What is Armor?
Armor takes all incoming physical damage and cuts out a percentage of it. There are some generally unimportant caveats regarding damage types. On the surface, armor looks difficult to understand. It really isn't.
Think of armor as increasing your own effective hitpoints instead of reducing incoming damage. For every one armor, a hero gains 6% of his current HP in against physical damage. So if you have 100 health and 1 armor, you can take 106 physical damage without dying. With 100 health and 20 armor, you can take 220 damage before dying.
I will use "effective hp", "effective health" or short "EHP" in reference to the amount of damage a hero can take from physical damage.
The Armor Era
As the meta swings back toward DPS-based cores ( Alchemist, 
Windranger, 
Spectre, 
Legion Commander are at the upper echelon of pickrate growth in pub Dota), armor and negative armor rise with them.
Applying negative armor increases your team’s overall physical damage output, so heroes such as 
Templar Assassin, Alchemist, and 
Slardar are on the rise alongside physical-damage drafts. For heroes like 
Dazzle or 
Lich, drafting positive armor when your opponents are likely to deal massive physical damage is central to survival.
Dota is an ecosystem and no hero’s popularity is truly one-dimensional, but armor's role in the current metagame has been a massive contributor to trending heroes.
Alliance vs Ninjas in Pyjamas game two from the Frankfurt qualifiers had a memorable example of negative armor's vital role (warning: spoilers in this section).
At 49:50, Alliance barely clings to life with their ancient under assault. Akke drops a death ward, which has a physical damage output, as NiP's Era tries to attack the ancient down. Alongside an army of creeps it will take him about 8 – 10 seconds to kill the ancient. Death ward would normally take about nine second to kill him given his EHP; the ancient should fall with a narrow margin of success. But Loda had already dropped Acid Spray, which helped zone NiP's heroes who didn’t want to stand in the Death Ward/Acid Spray combo. Now Era takes about seven seconds to die (without factoring regen).
In fact, none of NiP's heroes would live long enough to kill the ancient if they walked into the combination. The Acid Spray's negative armor helped create a situation where a comeback was possible.
Advanced Armor
Armor increases the value of raw HP and vice-versa. Each armor will always raise your EHP by 6% of your current HP, but that doesn't scale linearly when you consider EHP growth. There are diminishing returns to EHP growth from purchasing armor.
Warning: math to prove the point; you can skip it if you already believe me.
Let's imagine a hero with 1000 health and 0 armor. His effective HP is 1000. Now he buys 5 armor. His effective HP grows by 30% of his base HP, which is 300. He has 1300 EHP. He buys 5 more armor. His effective HP grows by 30% of his base HP again, still 300. He has 1600 EHP. In terms of EHP value, his health is going up linearly. In terms of his percentage growth of EHP, he is gaining less with each additional armor. The first five armor gave him 30% (300/1000) but the second five armor gave him 23% EHP growth (300/1300).
When Should I Buy Armor?
Casual Armor
It's okay to just buy an inexpensive, casual piece of armor for survivability and sell it later, especially for tanky heroes with an extra item slot. That option is far better than dying because you greedily saved to get a big-ticket purchase thirty seconds faster.
The Ratio Rule
Armor is typically better than HP if you have more than 1400 health. The exception is if you're against a heavily non-physical damage opponent, such as 
Silencer or [missing hero: outworld-devourer]. Armor has the best price-to-effect ratio in the mid game, but the highest impact in the late game. On average, armor items give about 1.6% effective hitpoints per 100 gold spent. Later game items do slightly better. HP and strength-based items give about 13 health per 100 gold spent in the early game, about half that in the mid game, and about double that in the late game.
The exact measurements will differ per item, this is just a loose guildeline. This is just to account for survivability, but doesn’t take into account other benefits of items.
So if you cross 800 base HP, it will be more cost effective to build items such as 
Ring of Basilius than 
Bracer to deal with physical damage. If you have 625 HP, it will be more cost-effective to buy items like 
Mekansm than 
Drum of Endurance. If you have 1400 HP, it will be more cost-effective to build late-game armor such as 
Shiva's Guard than late-game HP such as 
Eye of Skadi or 
Heart of Tarrasque. While in lane, armor is best if you have at least 775 HP. For pushing and teamfighting, it’s best if you have at least 435 HP.
The Nuclear Option
When deciding if you should buy armor, ask yourself how much health you’ll have after your opponents use their magic damage. Don’t factor your armor decisions on your max HP bar because you'll rarely fight without taking any magical or pure damage. Overinvesting in armor leaves you vulnerable to magical or pure-damage nukes.
For example, you're playing against a 
Lion with a level one Finger of Death. Add 625 HP to the HP you’d lose against Finger of Death (425) and 
Chainmail will typically give more survivability than Bracer at 1050 HP.
Jungle Sustain
Heroes who want to go to the jungle early benefit tremendously from small boosts of armor. Even a cheap 
Ring of Protection can extend your jungle sustain and will maximize the value of any health regeneration items. Since armor increases EHP as a percentage of your base HP, it also means that armor increases the value of consumables.
With no armor, the 400 HP from a salve offsets exactly 400 damage. With 5 armor, the 400 HP from a salve offsets 520 damage so it provides 30% more sustain while tanking creeps. Heroes who will tank jungle camps from level three or four and rely on the use of consumable regeneration, armor is an absolute must.
Armor on Strength Heroes
Strength heroes' high health pools make them perfect armor bearers. 
Tiny and 
Treant Protector are all examples of heroes whose core attributes and typical item builds give boatloads of raw hitpoints, and those heroes benefit the most from armor boosts.
A Ring of Protection on a level 12 Tiny with 
Aghanim's Scepter and Strength 
Power Treads will give him 330 more hit points against physical attacks. That’s seven times more cost effective than a 
Vitality Booster.
Armor on Agility Heroes
Heroes with high agility growth, such as 
Anti-Mage, 
Weaver, or 
Phantom Lancer will typically want to stay away from purchasing armor directly. These heroes tend to have very low strength gain, meaning they have low base HP.
In order to maximize their already great armor, they need to increase their HP (items such as Eye of Skadi, Heart of Tarrasque or 
Octarine Core). This is especially true later in the game where agility heroes will naturally have 16 – 25 armor. Agility carries also often build 
Manta Style. Although illusions retain the hero's base armor—so they benefit from agility increases—they do not benefit from armor purchases. This makes HP gains far more effective at increasing illusions' survivability.
Every seven points of agility give an agility hero one armor, in addition to increasing their attack speed and base damage, so if you need more armor it's typically more cost effective to purchase agility instead.
Armor on Intelligence Heroes
Int heroes tend to have moderate strength gain and low agility gain. They also typically avoid direct line of fire, trying to work around edges of fights, or initiate then fade back. Support Intelligence heroes should buy forms of armor that also help teammates, such as Ring of Basilius or 
Medallion of Courage. Consider this: a Ring of Basilius adds 12% hitpoints to all nearby allies for 500 gold. If your team has a total HP of 4000, the Basilius Aura will add 480 effective hitpoints. If you have more money to spare, you should of course never forget about 
Ghost Scepter, the ultimate protection against physical damage.
Cores usually benefit more from prioritizing raw HP or HP regen in order to be able to sustain damage (Octarine Core Leshrac, 
Bloodstone Storm Spirit, or Aghanim's Scepter Windranger).
Dealing with Armor
How to we stop tanky opponents who make strong build choices? Part of this comes down to draft and part to item builds, but here are the basic tools for those decisions. Heroes with both high health and high armor should have their armor reduced. Generally save nuke damage for more susceptible targets.
Heroes with high health and low armor can be handled by increasing physical damage alone.
Opponents with low health and high armor are the best targets for magical or pure damage nukes. Locking these heroes down is vital to killing them with attacks, but often not necessary if one or two solid bursts of magical damage are available (especially before Spell Shield or other forms of protection are available).
If your opponent has low health and low armor, you can kill him any way you want.
Is 
Solar Crest/ Medallion of Courage Still Good?
Yes, especially on Dire. Behind Ring of Basilius, Glimmer Cape, and Mekansm, Medallion of Courage is the most purchased support item in pro Dota. Medallion of Courage only has a 42.5% winrate in pubs, but that is because the losing team playing from behind is often the team that can’t afford to upgrade it to Solar Crest.
When you compare Solar Crest to similarly priced items (
Rod of Atos, 
Crimson Guard, or 
Pipe of Insight) it comes out ahead in success rate at about 65%. On the Dire side, a Medallion of Courage/Solar Crest can turn almost any successful fight into a free Aegis because of Dire’s ease of access to the pit.
As a caster, I’ve seen a lot of games lost because a Dire didn't have the negative armor to finish Roshan quickly enough. Why are these items so key as physical damage dealers become more prominent?
Against a 1500 health hero, Medallion of Courage reduces effective hitpoints by 630. In cases where units are guaranteed to stand still (for example, if they are Dueled), these items effectively act as after-the-fact nukes, like Orchid Malevolence. If you cast Medallion of Courage onto a hero who dies to Duel, you effectively hit him with a nuke worth 42% of his hitpoints.
Postscript (Mathing Armor with proof)
Formulas:
Damage multiplier = 1 – (0.06 * armor) ÷ (1 + 0.06 * |armor|)
Effective HP = Total HP * (1 + Armor points * 0.06)
Version of Alliance example from metagame section with math included: At 49:50, Alliance is clinging to life with their ancient under assault. Akke drops a death ward, which has a physical damage output, as NiP’s Era tries to attack the ancient down. With 2566 health and 24 armor, he would normally have 6261 effective HP against physical damage.
He’s dealing over 300 damage per second, so alongside an army of creeps it will take him about 8 – 10 seconds to kill the ancient, less with teammates. Death ward does 682 damage per second to each hero it hits. That means it would take about nine second to kill him. A very narrow margin of success on that defense. But he’s standing in Acid Spray, courtesy of Alliance’s Loda. That cuts his EHP to 5183 and allows them to kill him in about seven seconds. Better yet, any hero from NiP within attack range of the ancient is forced to stand in that acid, reducing all of their effective HP enough that the bounces from death ward would kill any of them before the ancient falls.
first
translate rus pls...fuking google translate
I think all this is missing is elaborating on which armor item to buy, for specific roles/situations and their utility that makes changes to cost effectiveness of the item.
booty jams
a good article but still have flaws , didnt mention about the items that should be bought for what role at what time, also , still need to mention the important to get early armor on INT heroes , not only those rings and medallion helps , vladr too , especially for junglers and supports
Translate to spanish pls
Gotta leave room for the sequel, yo. I gots rent to pay.
49:50? The video only has 10 mins of action
yea this article is 100% wrong.
armor has been rendered completely worthless by this game's rampant power creep. 10 armor or 40 armor, makes no difference - you will still die in a shackle, or a slardar stun, or an AM abyssal.
the only way to survive is to buy damage avoidance such as ghost, euls, force, glimmer.
Excellent article man Thanks!
Ogre magi is strength hero? This is new.
Conclusion: the best item for this meta is _assault_cuirass_
@star the one:
That was a mistake, whoops! Ogre has insane str gain though!
@ShAdOwDaRkSoU its not vdeo minute but in game minute
Technically speaking, your armor type does protect against magical damage (it's why most heroes have 25% base magic resistance). That isn't hugely important to know since it doesn't have mechanical impacts—reducing hero armor to 0 doesn't change the amount of damage it blocks from magic or cleave.
@Mekarazium where does it say that...? nowhere. exactly.
screw off any people asking for translations lmao
Really useful guide! I really should get more into the theory of dota...
@SE7EN
Да хорош тебе, и так всё понятно же. Много HP и брони? Уменьшай броню. Много HP, но не брони? Просто увеличь физический урон по нему. Мало HP, но много брони? Бей магией. Ни того, ни того — бей как угодно.
А, и не забывай про Solar Crest.
Вот вся суть :D
TA DAAAH
pretty good article.......GG :D
Thanks Gorgon. Nice article!
@Marshmallow - The Nuclear option
@Yellow Guy
you read that wrong. He doesn't say armor helps against magic/pure, he says you should factor it in when deciding if you should buy armor or HP.
example: Let's say you have enough armor to give you 20% increase in EHP against physical.
1) You have 1000Hp and the enemy removes 800 with magic spells which is ofc ignored by the armor. You have 200Hp left which they (generally) have to work through with rightclicks, because their spells are on cooldown. Your armor gives you 40EHP against physical dmg.
-> buying more hp will give you more EHP per gold than buying more armor. (You might not come to the same conclusion if you did the math with 1k HP instead)
2) Same example as above but you have 3k HP instead. After their spells you have 2,2k HP. Armor gives you 440EHP against physical dmg.
-> buying more armor will give you more EHP per gold than buying more HP.
@Gorgon
Cleave ignores armor
will bought cuirass every game then. ty
cleave ignores armor, but if the main target were in high armor, the cleave damage will be crippled cmiiw
@Kel'Thuzard
The damage from cleave is completely unaffected by how much damage the primary target takes.
If you have 100 damage and a battle fury and hit a unit with ~25 or so armor, so they only take 50 damage, the people behind them still take 35 damage from the 35% of your 100.
If you have 2 battlefurys and still 100 damage and hit the same guy he'll still take 50 damage from his armor reduction, but the people behind him with now be taking 70 damage, more than the guy that actually got hit. This is particularly noticeable with Kunkka since he's cleaving for 100% so the people behind the main target take much more than the primary target.
The only thing that works based off the damage the primary target takes is Templar Assassin's Psi-Blades.
instruction unclear, got myself buying rapier instead
@BD You sir are wrong. EHP matters a lot because it takes longer to kill you (when its not magical damage). Meaning they need a longer shackle or stun to kill you. It would be the same with a ghost scepter, Why would you have one if you are stuned and cant activate it in time? While armor gives you time to react and live longer!
@giselachar20 technically not true. It is "reduced by armor type," which is effectively a reduction of 0 in post WCIII days.
"The damage is not reduced by the armor value, only the armor type and damage block reduce it."
http://dota2.gamepedia.com/Cleave
I'll throw a Deso or AC on just about any hero these days.
Awesome article dude :D
TRANSLATE
So bristle 80 armor in my next game.
Very insightful, thank you
EXPERIMENT: I once tried in "Demo Hero" using Dazzle and Stack his ulti on enemy axe; i first tried to Double cast it using Refresher (to make it realistic) and waited until the buff is almost done, and then hit Axe.. i measured the damage of that hit.. and then the second time, im on "Free spells Mode" i cast Dazzle's ulti on enemy Axe Countless times.. his armor is down by hundreds, and then i did the same thing as the first.. i waited until the buff is almost done, then hit Axe at the last second of the buff.. Guess what, the damage done is the same.. do this experiment too.. Then please someone explain..
@Nayn, what you're talking about is probably the diminishing effect of armor increase/decrease, same as in the article, armor increases or reduces EHP which is based on your base health, meaning:
1. Axe 1k hp +20 armor is 3000 EHP
2. Axe 1k hp 0 armor is 1k EHP
3. Axe 1k hp -10 armor is 625 EHP
4. Axe 1k hp -20 armor is 333.(3) EHP
5. Axe 1k hp -100 armor is 142 EHP
You can see that the initial -10 to -20 armor significantly reduces the EHP of Axe, while decreasing the armor by -100 doesn't give half of the benefits of lowering armor.
p.s. Even with full - armor squad (SF -6 armor, Slardar -20 armor, Deso -7 armor, Solar crest -10 armor, AC -5 armor, Dazzle -1 to -30 armor) it equals to maximum -78 armor, if you add bristle then its max -85 or something. This is not even worth trying to achieve since the enemy team would then have no other option than to split push, and remember that you have to farm up all these items, plus if they have nuke spammers like lina zeus or qop they can easily take down a squishy sf with 1.5k hp regardless of how much armor he has.
Finally, the whole point of this article is get Windranger, farm aghs, desolator, solar crest, daedalus, mkb (in this order) and kill any hero which will appear.
@nayn Because the double ult already does -60 or -84 armor (depending on if you have aghs on dazzle or not), adding a third or fourth instance of weave will not make much of a difference. Like the article says, with each point of armor it gets less and less effective with adding EHP. The same goes for minus armor, see http://dota2.gamepedia.com/Armor .
Personally what I feel missing in this article is awareness of when to buy armor and when to buy raw hp. For me as a core versus a balanced magic damage and physical damage line up I tend to aim at around 20-40 armor, after that I will just get myself more hp. Since armor has diminishing returns the more you have and raw hp doesn't: a point booster will always add the same amount of hp. Plus you still need some sustain in fights (or out of them): yes armor might do more for your EHP compared to a heart, but a heart enables you to rejoin fights much quicker or keep pushing after you've won a fight. Or lifesteal (especially on heroes with a crit), it might not give you raw hp or armor, but simply because you add hp after each hit, it also makes you more 'tanky' or better said, sustainable in fights.
All in all you need hp, armor, some form of sustain or regen and maybe magic immunity to be able to fight in dota. The key is to know when to buy what.
Dunno if some adm reads this comments, but... There is any problem if I translate this article and make a video in portuguese to explain this concept? Brazilian community have few things like this but i'm not able (I'm not a good enough player) to "create" by myself. I'll refer u (dotabuff and Gorgon) of course.
ty) it was interesting
author
BOT Skim
really good article , i enjoyed it , i understand what u mean
and about other people that keep telling this article useless , let him be
im happy about that , coz its easier for me if the world dont understand about how important armor
i want talk a lot about minus armor to support ur statement , but i want other people still careless about armor
maybe i have clue a bit
why pro player always buy medallion
why slardar currently be a top pick , beside his sprint offlaner
why secret can win the game with slardar misery at grandfinal nanyang champ
why clinkz's fear use medallion + deso build
why sf winrate a bit high in pub match
why pro player use slardar to counter alche
and if someone want to share this armor article , i think its ok
Currently the Enchanted Mango only has a 36.93% win rate. Together, we as a community, have the ability to fix this problem and end this horrific tragedy. Please help. It is our duty as gamers to give this item the respect it is due.
Very good post, especially for modest players like me, even if I knew the importance of armor.
If you're playing against Techies you gotta buy armor. I remember playing Doom against Techies. I got an AC, +20STR from Halberd and +4STR from a Wand. My team was standing behind me while I was clearing mines lol. Unfortunately, we lost because of my reatarded teammates (double ac and vlads...).
That's a good example of why armor is so damn important
Waw just get Deso, AC on SF, Dazzle tosses ult and medallions u while u walk in and 3-4 hit everything..
"Armor increases the value of raw HP and vice-versa. Each armor will always raise your EHP by 6% of your current HP, but that doesn't scale linearly when you consider EHP growth. There are diminishing returns to EHP growth from purchasing armor." While this is correct, it is exactly the same for HP. I think the main point is that you have to weigh which types of damage you are facing and itemize accordingly.