Complete Guide to Armor, Damage Reduction, and EHP

[[S2]MacroHard]

Contents

• Preface - What and why
• Damage Reduction and Damage Factor - How armor reduces incoming damage
• Offensive Damage Amplification - The "sweet spot" for armor reduction
• Effective Health and the Linearity of Armor - How the benefits of armor are linear (not diminishing)
• "Diminishing" Returns of EHP - The illusion of diminishing returns
• Incremental Benefits of Health and Armor - The benefits of 1 extra HP or armor
• Lines of Equivalency - How much health a single point of armor is equal to
• Optimization and Adjustments for Fixed Magic Damage - How to optimize your gold for maximum EHP for fixed incoming magic damage
• Optimization and Adjustments for Scaling Magic Damage - How to optimize your gold for maximum EHP for incoming damage as a percentage of total damage
• Health/Armor Balance Quick Reference - Easy to read rule of thumb that quickly summarizes all of the above
• Conclusion - Meaningless generalities
• Item EHP Tables - 60 individual tables itemizing the EHP and EHP/gold for every item in HoN
• FAQ - Your questions answered

Preface

Armor is one of, if not the most, under appreciated and underrated attributes in HoN.

After searching through the threads, stickied posts, and google searches, I still could not find a guide truly dedicated to unraveling the mysteries of EHP specific to HoN. The closest guide that met my standards, by Malle, was mostly focused on comparing armor to shield blocking. While brilliant, it still didn't quite get the message out on the true value of armor. Malle's guide can be read here: http://forums.heroesofnewerth.com/sh...09#post=444209.

I am aware that these formulas are commonly available and have been hashed out many, many times before. The first few sections of this guide are just for ease of reference and overall consolodation. Please continue to the end of this guide for newer revelations.

Damage Reduction and Damage Factor

for positive armor:
DR = 0.06*A/(1 + .06*A)
DF = 1/(1+0.06*A)

for negative armor:
DR = 0.94^(-A) - 1
DF = 2 - 0.94^(-A)

These are the basic formulas that are the building block of effective health. All of these formulas are available on various threads and guides on the mechanics forum and honwiki. They are repeated here for your convenience.

Definitions

Health HP
Health is the in-game attribute that determines your capacity for life. When health drops to zero your hero dies. Maximum health increases with strength (19 health for every 1 strength), can be purchased directly, or enhanced by skills/spells.

Armor A
Armor is the in-game attribute that is used to calculate Damage Reduction. Higher armor corresponds to more damage resistance. Armor increases with agility (.14 armor for every 1 agility), can be purchased directly, or enhanced by skills/spells.

Damage Reduction DR
DR is how much, by percentage, incoming damage is reduced. For example, a DR value of 25% reduces one-fourth of damage. DR increases with armor. Both physical and magical armor work the same way, but against different damage types.

Damage Factor DF
DF is how much damage an attack actually does as a proportion of the listed damage. For example, for DF = 0.60, a 200 damage attack will only remove 120 health from the target. DF = 1 - DR.

Damage Reduction Formulas, Table, and Graph

Damage Reduction DR
DR = 0.06*A/(1 + .06*A), A > 0
DR = 0.94^(-A) - 1, A < 0
note: For this equation, since A < 0, -A will be positive

Table:


Graph:

Damage Factor Formulas, Table, and Graph

Damage Factor DF
DF = 1/(1+0.06*A), A > 0
DF = 2 - 0.94^(-A), A < 0
note: For this equation, since A < 0, -A will be positive

Table:


Graph:

Offensive Damage Amplification

When talking about DPS, all you care about is how fast you can eliminate the opponent. If the enemy has 20 armor, how much faster can I kill him with Shieldbreaker Level 2? If the enemy has -5 armor because of Pesti ultimate, is it really worth buying Sol's Bulwark? These questions can be answered by looking at when armor makes the enemy most vulnerable to physical damage.

This section identifies the "sweet spot" where armor reducing items and spells have the biggest effect. This sweet spot is typically between 3 and 5 armor. You can also see that armor reducing items and spells still maintain usefulness even into the negative armor range.

Definition and Example

Damage Amplification
Damage Amplification will be defined, for the sake of this guide, the rate of change of the Damage Factor with respect to Armor, divided by the original Damage Factor. It is essentially the increase of damage on a percentage basis.

For example, the enemy has an armor value of 15 and you intend to decrease it by 5.
DF(15) = 1/(1+.06*15) = 0.526 = 52.6%
DF(10) = 1/(1+.06*10) = 0.625 = 62.5%

The increase in Damage Factor is 9.9%.
However, the Damage Amplification is (0.625-0.526)/(0.526) = 18.8%.

By lowering the enemies' armor from 15 to 10 you will kill them 18.8% faster.

Formula

For negative armor,
DF = 2-0.94^(-A)
-dDF/dA = 2489*2^(A-1)*5^(2*A)/(20113*47^A)
-dDF/dA / DF = 2489*2^(A-1)*5^(2*A)/(20113*47^A)/(2-0.94^(-A))

For positive armor,
DF = 1/(1+.06*A)
-dDF/dA = 150/(9*A^2+300*A+2500)
-dDF/dA / DF = 150/(9*A^2+300*A+2500)*(1+.06*A)

Table, General Case

Graph, General Case

Table, Item Specific

This shows the total Damage Amplification from Shieldbreaker and Sol's Bulwark.

Graph, Item Specific

Effective Health and the Linearity of Armor

Effective Health, or EHP, is another commonly referred to factor along with Damage Reduction. EHP is more meaningful to reality however, as explained in the definition below. Once again these formulas are repeated here for your convenience.

Definition

Effective Health EHP
EHP is the amount of unmitigated damage you can take before dying. For example, it takes 20 attacks of 200 listed damage to kill a target with 4000 EHP. Due to this direct relation to unmitigated incoming damage EHP is the single best measurement of survive-ability. Both Health and Armor contribute to the calculation of EHP.

Effective Health Formula

EHP = HP/(1 - DR) = HP/DF = HP*(1 + .06*A), A > 0
EHP = HP/(1 - DR) = HP/DF = HP/[2 - 0.94^(-A)], A < 0
note: For this equation, since A < 0, -A will be positive

Tables

Graphs

Linearity

As shown in the graphs, the benefit of armor is purely linear for positive armor even though damage reduction is diminishing.

Every additional point of armor gives the same benefit as the point before.

In other words, going from 5 to 6 armor has the same benefit as going from 45 to 46 armor. Not only is there no functional armor cap, there is not even an upper bound where armor becomes less effective.

To prove this with the formulas, let's take the example above with 2000 health:
2000 HP and 5 armor gives 2600 EHP
2000 HP and 6 armor gives 2720 EHP... a gain of 120 EHP
2000 HP and 45 armor gives 7400 EHP
2000 HP and 46 armor gives 7520 EHP... also a gain of 120 EHP

"Diminishing" Returns of EHP

While total EHP increases linearly with armor, the percentage of EHP gain compared to current EHP naturally decreases. The same applies for every attribute in HoN. For example, increasing Health (or EHP, or mana, etc) from 1000 to 1100 is a gain of 100 or 10%. However, increasing Health from 2000 to 2100 is still a gain of 100 but now only 5%.

For example, if you already have 20 armor, 1 additional point of armor will increase your EHP by 2.7%, NOT by 6%.

Calculation

%EHP gain is calculated by taking the dirivative of the EHP formula and dividing the result by the EHP formula.

For negative armor,
EHP = 1/(2-0.94^(-A))
dEHP/dA = 2489*2^A*47^A*5^(2*A)/(20113*5^(4*A)*2^(2*A+1)-20113*47^A*5^(2*A)*2^(A+3)+160904*47^(2*A))
%EHP = dEHP/da / EHP = [2489*2^A*47^A*5^(2*A)/(20113*5^(4*A)*2^(2*A+1)-20113*47^A*5^(2*A)*2^(A+3)+160904*47^(2*A))]*(2-0.94^(-A))

For positive armor,
EHP = (1+.06*A)
dEHP/dA = 0.06 (somewhat easier than negative formula!)
%EHP = dEHP/dA / EHP = 0.06/(1+.06*A)

Table

Graph

Incremental Benefits of Health and Armor

This is the first step towards understanding how to maximize EHP. In order to optimizing the balance between Health and Armor, we must first identify exactly the benefit, in terms of EHP, from one additional unit of Health or Armor.

HP's incremental effect on EHP: (increase in EHP) = (additional HP)*(1 + .06*A)

(original EHP) = (original HP)*(1 + .06*A)
(new EHP) = (original HP + additional HP)*(1 + .06*A)
(increase in EHP) = (new EHP) - (original EHP) = (additional HP)*(1 + .06*A)

Armor's incremental effect on EHP: (increase in EHP) = .06*HP*(additional A)

(original EHP) = HP*[1+.06*(original A)]
(new EHP) = HP*{1 + .06*[(original A)+(additional A)]}
(increase in EHP) = (new EHP) - (original EHP) = .06*HP*(additional A)

Lines of Equivalency

For every given Health and Armor combination, there is a precise ratio at which X Health is equivalent to Y Armor.

Each "line of equivalency" is:
(additional HP)/(additional A) = .06*HP/(1 + .06*A)

Explanation

Set incremental EHP gain from Health equal to incremental EHP gain from Armor:
(additional HP)*(1 + .06*A) = .06*HP*(additional A)
(additional HP)/(additional A) = .06*HP/(1 + .06*A)

For example, if you currently have 15 armor and 2000 health, increasing armor by 1 is equivalent to increasing health by 63.2. To put it in more game-real quantities, increasing armor by 5 is equivalent to increasing health by 316.

Table

Graph

Optimization and Adjustments for Fixed Magic Damage

By assigning in game currency, gold, to each incremental point in Health or Armor, we can calculate a single line of Health/Armor optimization.

It is important to note that this gold assignment is subjective. My calculations and graphs are based on 1 HP = 4.4 gold and 1 Armor = 110 gold.

Using this assumption, the optimal balance of Health and Armor is:
A = 0.04*[HP-(Anticipated Magic Damage Received)] - 16.67

Assumptions

Fortified Bracelet = 510 gold, 114 HP -> 4.47 gold/HP
Beastheart = 1100 gold, 250 HP -> 4.40 gold/HP
Ringmail = 550 gold, 5 A -> 110 gold/A

Although there are many items that give armor and/or HP, I am assuming that the portion of the cost of these items directly responsible for health and/or armor fall within these same ratios.

For instance, Frostfield Plate costs 4700 gold and gives 15 armor. The cost per armor is not 313. Rather, I am assuming that the cost associated with 15 armor is only 1650 gold. The remaining 3050 gold for this item go towards the other benefits for that item (int, mana, active, etc).

Calculation

(additional HP)/(additional A) = .06*HP/(1 + .06*A)
(1/4.4)/(1/110) = .06*HP/(1 + .06*A)
25 = .06*HP/(1 + .06*A)
A = 0.04*HP - 16.67

This works fine for when 100% of the damage you take is physical. However, there is a lot of magic in HoN. Therefore you must account for the post-mitigated magic damage you anticipate to absorb in a fight. This damage deducts from your health such that the formula becomes:
A = 0.04*[HP-(Anticipated Magic Damage Received)] - 16.67

Graph

Example

You have 2000 HP. Based on the enemy team composition, you expect to receive 1000 damage after reductions in a particular teamfight.

Using the 1000 damage line, you should have about 23 physical armor for an optimal balance between health and armor.

Optimization and Adjustments for Scaling Magic Damage

Similar to above, this section uses the same gold assumptions of 1 HP = 4.4 gold and 1 Armor = 110 gold.

This time, rather than a fixed amount of magic damage, the balance is calculated using the percentage of incoming damage that is magical.

Calculations

Let X = percentage of incoming damage that is magical (.25 = 25% of unmitigated damage received is magic)
Let M = magic armor

Amount of Magic Damage = X/DF = X/(1+.06M)
Amount of Physical Damage = (1-X)/DF = (1-X)/(1+.06A)
Effective Combined Damage Factor = X/(1+.06M) + (1-X)/(1+.06A)
Effective Combined EHP = HP/DF = HP/((1-X)/(1+.06A)+X/(1+.06M))

Value of HP = ((H+1)/((1-X)/(1+.06A)+X/(1+.06M)) - H/((1-X)/(1+.06A)+X/(1+.06M)))/4.4
Value of A = H/((1-X)/(1+.06(A+1))+X/(1+.06M)) - H/((1-X)/(1+.06A))+X/(1+.06M))

Setting these equal yields the following solution for H in terms of A:
HP = (3AX-3M(X-1)+50)((3A+3)X-3M(X-1)+50))/((1-X)/(1+.06A)+X/(1+.06M))/4.4/(3M+50)^2/(1-X)/.06/110

Graph

Example

You have 2000 HP and 10.5 magic armor. Based on the enemy team composition, you expect half the damage you receive will be magical (X = 0.5).

Using the X = 0.5, M = 10.5 line, you should have about 18 to 19 physical armor for an optimal balance between health and armor.

Health/Armor Balance Quick Reference

Let's face it. Looking at multiple graphs, tables, and charts is silly and impractical while in a game. While it makes for an interesting thought experiment while cruising the forums, nobody will ever think "okay, if I'm going to take X amount of magic damage, my next item purchase should be...".

To address this, I put together a "Hybrid" method - a single simple graph that combines the essence of everything you've learned up until this point. The result is a continuous line that simply lets you know if you're in the right ballpark for efficient EHP gain. If you frequently stray from this line perhaps you have a tendency to invest too much in Health or too much in Armor. Remember, balance is key.

WARNING! Hard numbers and math end here. What follows is purely subjective!

What is This?

If you look at the optimization lines, how likely is it that you will take 1500 magic damage at a point in the game where you are still sitting on 750 health? Zero. The following table and graph is essentially a smoothed line based on the fact that magic is more prevalent early game.

Table

Graph

Example

You have 2000 HP. The enemy team is more physical based than usual, but there are still some magic sources.

Using the graph and estimating between the "Heave Physical" and "Typical" lines, you should have approximately 20 physical armor for an optimal balance between health and armor.

Conclusion

Because magic damage is more prominent early game, armor is mostly not necessary very early game until your health reaches around 1000. However, after that point, armor's economic effectiveness skyrockets. Even with expecting to take a whopping 1500 magic damage after mitigation, you should have about 23 armor by the time you hit 2500 HP. Keep this in mind next time you contemplate building your hero to have 3500+ health. More often then not you are better off buying some simple armor items if your goal truly is to be as tanky as possible.

• The benefits of Armor are completely linear and there is no upper bounds for armor
• Armor is often the least expensive way to increase EHP
• High Health / Low Armor has the advantage of providing better protection against magical attacks
• High Armor / Low Health makes better use of health regeneration items and spells

[[S2]MacroHard]

Item EHP Tables

This section tabulates the additional EHP an item gives. It factors in Health, Armor, Regeneration, Blocking, Evasion, and even the amount of unmitigated incoming damage. The tables are sorted in descending order by EHP per gold.


Assumptions

• 10 second duration when factoring in Health Regeneration
• Health regeneration of 3 HP/sec prior to item purchase
• No evasion or blocking prior to item purchase (whether from other items, spells, or skills)

EHP Factors

H - Health
A - Armor
R - Health Regeneration
T - Health Regeneration Time (10 seconds)
D - Unmitigated Incoming Damage (affects damage block)
S - Strength of Item (adds to health and health regeneration)
A - Agility of Item (adds to agility)
B - Shield Blocking value
%B - Shield Blocking chance
%E - Evasion chance


Formula

EHP = (H+RT)*D/X
X = Average Mitigated Damage = [F*(D-B)*(%B)+F*D*(1-%B)]*(1-%E)
F = Damage Factor = 1/(1+.06*A)
Note:
This formula gives the total EHP; the values in the tables below reflect the difference in total EHP from before and after acquiring the item.


Tables

Tables are broken up as follows:
D = {75, 150, 225}
H = {500, 1000, 1500, 2000, 2500, 3000}
A = {0, 2, 5, 10, 15, 20, 25, 30, 35, 40}
Note:
Not all permutations are used. Unlikely extremes are omitted (for example 3000 HP and 0 armor at the same time).

D = 75

H = 500

A = 0

A = 2

A = 5

A = 10

A = 15

H = 1000

A = 2

A = 5

A = 10

A = 15

A = 20

H = 1500

A = 5

A = 10

A = 15

A = 20

A = 25

H = 2000

A = 10

A = 15

A = 20

A = 25

A = 30

D = 150

H = 1000

A = 2

A = 5

A = 10

A = 15

A = 20

H = 1500

A = 5

A = 10

A = 15

A = 20

A = 25

H = 2000

A = 10

A = 15

A = 20

A = 25

A = 30

H = 2500

A = 15

A = 20

A = 25

A = 30

A = 35

D = 225

H = 1500

A = 5

A = 10

A = 15

A = 20

A = 25

H = 2000

A = 10

A = 15

A = 20

A = 25

A = 30

H = 2500

A = 15

A = 20

A = 25

A = 30

A = 35

H = 3000

A = 20

A = 25

A = 30

A = 35

A = 40

[[S2]MacroHard]

FAQ
to be populated based on responses in this thread

Q: I currently have 2000 HP. Approximately how much Armor should I have?

According to the Hybrid Approach table, an armor value of around 17 or 18 is a good balance for defending against all sources of damage in a typical game. Keep in mind this is just an approximation; depending on your enemy lineup you may need much less or much more than this. However, this value is an excellent starting point for typical scenarios. Use it as a gut check to make sure you are in the right ball-park.

Q: How do you determine whether its "best" to spend my gold on more Health or more Armor?

However, the only thing i am missing is a chart whether its better to get more HP or more Armor if you got a certain amount of HP and Armor. For example i got like... 1500 HP and 7 Armor will i get more EHP if i buy Armor or HP.

Find your point in the "Lines of Equivalency" graph. At 1500 HP and 7 Armor, the graph shows that 1 Armor is equal to about 63 HP. So buying a Ringmail (5 Armor) is equivalent to increasing your health by 315. But this only applies to physical damage and does not factor in gold cost.

The answer to the gold effectiveness is in the "Gold Burden and Economic Normalization" graph. First you have to identify how much magic damage you think you'll sustain. At 1500 HP and 7 Armor, it's early game, so let's use 750 magic damage line. Follow the imaginary curve (halfway between the 500 and 1000 magic damage lines) to where it intersects 1500 HP. This equals about 13 armor. Since you only have 7 Armor, you are behind in Armor and therefore it's more cost efficient to buy Armor than HP if your goal is EHP.

Q: Will stacking health be more beneficial considering the regeneration of Behemoth's Heart?

EHP calculations ignore regen, usually. I agree that armor is still better, but when people stack HP like that they usually are looking to get a really high HP regen rather than just general survivability. It's still bad, but not as bad as you might think: :fors:

Regeneration, even from max HP based Behemoth's Heart, actually favors sacrificing HP for armor. This is because each point of HP regenerated works harder and lasts longer with ample armor. Let's factor in regen using the example of :BehemothsHeart: :BehemothsHeart: :BehemothsHeart: vs :BehemothsHeart: :FrostfieldPlate: aemonicBreastplate on a Hero with 111 strength, 15 armor, and no other health or regen items.

:BehemothsHeart: :BehemothsHeart: :BehemothsHeart: = 5004 HP, 15 Armor, 44 regen
:BehemothsHeart: :FrostfieldPlate: aemonicBreastplate = 3074 HP, 45 Armor, 27 regen

Not factoring in regen:
5004 HP -> 5004 HP and 15 armor = 9508 EHP
3074 HP -> 3074 HP and 45 armor = 11374 EHP
1866 EHP increase

15 seconds of regen:
5004 HP -> 5664 HP and 15 armor = 10762 EHP
3074 HP -> 3479 HP and 45 armor = 12872 EHP
2110 EHP increase

30 seconds of regen:
5004 HP -> 6324 HP and 15 armor = 12016 EHP
3074 HP -> 3884 HP and 45 armor = 14371 EHP
2355 EHP increase

The more you utilize your regeneration, the more the lack of regeneration pays off. Counter-intuitive but true!

[Boltzen]

Awesome, fully in depth and so, so detailed. I don't see how you can improve this.
Also, there is a small typo "reaces" in the conclusion paragraph.

[[S2]MacroHard]

Thank you. Fixed typo.

To me, EHP was something everyone was supposed to take for granted. There were equations and graphs here and there, but I was never happy with any one guide. I asked ElementUser if I could make my own and he told me to go for it.

The reserved post #2 is going to be epic an exhaustive list of every item's EHP/gold for every Armor/Health combination, but it'll take me about a week to finish it. In the meantime I wanted to share the basics and get the conversation going.

[Xenp]

Oh man you are fast on your typo correction - second time I've gone to post and it's been fixed while I was reading through it =P


Amazing job btw

[[S2]MacroHard]

If any of you have any questions, doubts, recommendations, or requests, let me know. I want this to be as clear, complete, and helpful as possible.

edit: or confusion or clarification

[Connect]

Good lord.. Wauw. Nice job mate!

[[S2]ElementUser]

clap.gif!

[FlyingFury]

Awesome. Also u have a typo in definitions in DF where it says how much an "attack doesactually does"

[Sultax]

first

[Fair]

Sticky! :O

[apm120]

TLDR?

i got that you better of getting magic armor if over 1000hp....what about normal armour?

[[DrQs]xDries]

TLDR?

i got that you better of getting magic armor if over 1000hp....what about normal armour?

Troll right? Just read the whole thing -_-'

[[STU]Mc_Muffin]

Really nice and interesting post.

The Only thing that kinda confused me was the last part about "Gold Burden and..." which may come from my english

However, the only thing i am missing is a chart, where you can see, whether its better to get more HP or more Armor if you got a certain amount of HP and Armor.

For example i got like... 1500 HP and 7 Armor will i get more EHP if i buy Armor or HP. I am quite sure that this is able to calculate, i only would have to start thinking about it (which i dont want to ATM )

Its also possible, that that is what stands in the last part of you post, since i didnt really get that part

But anyway: nice post

[[Epz]matruder]

Awesome post

[[S2]MacroHard]

Awesome. Also u have a typo in definitions in DF where it says how much an "attack doesactually does"

Thanks. Fixed.

Really nice and interesting post.

The Only thing that kinda confused me was the last part about "Gold Burden and..." which may come from my english

However, the only thing i am missing is a chart, where you can see, whether its better to get more HP or more Armor if you got a certain amount of HP and Armor.

For example i got like... 1500 HP and 7 Armor will i get more EHP if i buy Armor or HP. I am quite sure that this is able to calculate, i only would have to start thinking about it (which i dont want to ATM )

Its also possible, that that is what stands in the last part of you post, since i didnt really get that part

But anyway: nice post

Find your point in the "line of equivalency" graph. At 1500 HP and 7 Armor, the graph shows that 1 Armor is equal to about 63 HP. So buying a Ringmail (5 Armor) is equivalent to increasing your health by 315. But this only applies to physical damage and does not factor in gold cost.

The answer to this is in the last graph. First you have to identify how much magic damage you think you'll sustain. At 1500 HP and 7 Armor, it's early game, so let's use 750 magic damage line. Follow the imaginary curve (halfway between the 500 and 1000 magic damage lines) to where it intersects 1500 HP. This equals about 13 armor. Since you only have 7 Armor, you are behind in Armor and therefore it's more cost efficient to buy Armor than HP if your goal is EHP.



Good question. Added to FAQ.

[[STU]Mc_Muffin]

awesome dude
tbh i never really checked my armor and instead just bought mass hp (if i chose to go tanky) your thread really fixed that...thanks man

greetz Mc_Muffin

[[S2]MacroHard]

awesome dude
tbh i never really checked my armor and instead just bought mass hp (if i chose to go tanky) your thread really fixed that...thanks man

greetz Mc_Muffin

This is why it is *never* good to buy more than one Behemoth Heart (I still see this in some trash games).

For example, take a no-stats all mid game where everyone eventually gets max farm. You see Legionnaires or Devourers walking around with 3 Behemoth Hearts thinking they're unkillable with 5000 HP. Well the truth is they would be even more un-killable with a Behemoth Heart, Demonic, and Frostfield Plate.

5000 HP and 15 armor = 9500 EHP
3070 HP and 45 armor = 11359 EHP

Almost a 20% increase in EHP... and that doesn't even account for the decreased enemy attack speed from Frostfield, the AOE damage and slow from Frostfield, the huge mana supply from Frostfield, the massive attack speed from Demonic, the AOE attack speed from Demonic, the AOE armor (and EHP) of Demonic, and the AOE -armor (and -EHP) that the enemy now suffers.

Cool huh?

[Zwai]

This is why it is *never* good to buy more than one Behemoth Heart (I still see this in some trash games).

For example, take a no-stats all mid game where everyone eventually gets max farm. You see Legionnaires or Devourers walking around with 3 Behemoth Hearts thinking they're unkillable with 5000 HP. Well the truth is they would be even more un-killable with a Behemoth Heart, Demonic, and Frostfield Plate.

5000 HP and 15 armor = 9500 EHP
3070 HP and 45 armor = 11359 EHP

Almost a 20% increase in EHP... and that doesn't even account for the decreased enemy attack speed from Frostfield, the AOE damage and slow from Frostfield, the huge mana supply from Frostfield, the massive attack speed from Demonic, the AOE attack speed from Demonic, the AOE armor (and EHP) of Demonic, and the AOE -armor (and -EHP) that the enemy now suffers.

Cool huh?

EHP calculations ignore regen, usually. I agree that armor is still better, but when people stack HP like that they usually are looking to get a really high HP regen rather than just general survivability. It's still bad, but not as bad as you might think: :fors:

If it was purely armor vs. hp, then regen wouldn't matter because it would end up just being another multiplier. But there is magic, physical, true, and hp removal damage in the game and you can only get armor for 2 of those. Physical is your main worry when it gets to that point, yes, but if your opponents are heavy casters and you're already tiered out on magic armor it doesn't sound that bad to just stack HP. A Soul Reaper or Scout can still do heavy magic damage lategame, after all. What if they have a Pestilence with Shieldbreaker, and a Puppet Master with Harkon's?

For what it's worth, I tend to get a Sacrificial Stone or Frostwolf Skull on Devourer rather than a second or third heart(if I'm stacking HP in a pub game), simply because the extra regen is so important on a heart and you don't get that with the extras.