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caspian

Imperator Posts: 2452 Joined: 27 Mar 2007 gold

Armor-Damage System Walkthrough

Posted: Tue May 27, 2008 2:09 pm

Foreword

This topic will deal extensively with damage and how it is reduced (or amplified) in relation to armor type, attack type, damage type and other miscellaneous factors. It does not discuss the relation of armor with hitpoints so calculations on subjects like Effective Hit Points are not included here.

Even though various similar topics will appear in other DoTA forums, the following discussions are mathematically and factually related, and so cannot be copyrighted by any author. Only tables and images which are copied from other sources can be copyrighted and protected from plagiarism.
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Factors that determine the amount of damage that can be dealt towards a unit

In DoTA generally there are 4 main factors that actually determine how much damage a unit can receive. We will limit ourselves to what is relevant to DoTA as certain modifiers in Warcraft 3: The Frozen Throne are different.

a) Armor value reduction or amplification
b) Armor type and attack type
c) Damage type
d) Miscellanous factors

Conclusion
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a) Armor value damage reduction or amplification

Armor value refers to the “number” that is shown on the “Armor” property inside a unit’s display panel at the bottom of the screen. Obviously the higher the armor value the higher the damage reduction. Sometimes armor value can be reduced or even made to become negative, in which case any damage dealt will be amplified.

According to Battle.net, damage reduction via armor value is calculated through a mathematical formula that is as follows: (Please click on image to view it in full size)

The same goes for the negative:

For negative armor damage amplification however, the damage increase cannot go beyond -20 armor. At -20 armor, damage amplification is 71% - the maximum. Beyond that (eg. -26 armor), the damage amplification will not increase.
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b) Armor type and attack type

What follows is very important and determines our understanding of this system of armor versus damage issue:

Armor value as a factor in determining output damage is intrinsically different from armor/attack type. Both are independent of each other and do not work the same way.On one hand the percentage of damage reduction /amplification is related to armor value as can be observed in the above formulae. But in the case of armor/attack type a set of tables exists which fixes damage dealt at a constant rate.

A common example of armor type damage reduction is Hero armor reducing Spell type attack by 25%, ie. reducing damage done by spells by 25%. The following table illustrates the damage modifiers against various armor types by various attack types:

What does the table essentially explain? The mathematical values explain how much the intended damage issued by the attack type would be multiplied against the targeted armor type.

Taking the Attack type Hero row as an example, any attack done under this type (eg. heroes) will retain 100% of its damage against Light armor units, 100% against Medium armor, 100% against Heavy armor, 50% against Fortified armor, 100% against Normal armor, 100% against Hero armor and 100% against Unarmored units. However this damage multiplier does not influence the damage reduction from armor value, so the resultant damage will still be affected by the armor value of the target.

If a hero has 100 damage, and attacks an enemy tower (Fortified Armor) which has 18 armor (ie. 52% damage reduction), the correct way to calculate the output damage would be to first multiply it with the damage multiplier – in this case 0.5 – and then take the result and multiply it with (1 - damage reduction)

Therefore a Hero type attack of 100 damage against Spirit Tower Level 1 would produce an output damage of:

Damage = 100 x 0.5 x (1 – 0.52) = 24 damage

In another example, Siege attacks deal 1.50 damage versus Fortified Armor, which means any attacks done by the Glaive Thrower or Meat Wagon (both of which have Siege attacks) would deal 50% more damage against Towers, which have Fortified armor. This does not take into account the quantity value of the armor which would have reduced damage by itself.

Another interesting implication from the above table, and also from the italicized quote above, is that Chaos attack deal 1.00 damage to all armor types except Fortified, but at the same time this attack, depending on the Damage Type of the attack (which will be discussed later), can be further reduced by armor value.

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c) Damage Type

Basically under the Damage Type factor all sources of damage can be classified as:

1. Normal
2. Magic

Normal damage refers to damage that can be reduced by armor value (Factor (a)) and Magic damage refers to damage that ignores armor value but can be nullified by magic immunity.

Therefore this factor implies that some damage can be blocked simply by being magic-immune. A good example of this kind of damage is the Enchantress’ Impetus bonus damage, which falls under the category of Hero type attack, Magic type damage. Hero type attack means that this type of attack does 100% damage to heroes, while Magic type damage means that this type of attack will not work on magic-immune units.

An example of Normal type damage is Dwarven Sniper’s Scattershot – Piercing type attack, Normal type damage. The Piercing attack implies that it does a lot of damage against creep waves (Unarmored) but less damage against heroes, while its Normal damage type implies that it can be reduced by armor value – which explains why the spell is not very effective against heroes.

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d) Miscellanous factors

Aside from the above there are also a number of other factors that can determine damage:

i. Evasion
ii. Damage block
iii. Miscellaneous damage amplification
iv. Miscellaneous damage reduction

Evasion reduces damage by making damage dealers miss on some of their attacks. Some of these items or abilities include the Butterfly, Troll Warlord’s Blind, Phantom Assassin’s Blur, etc.

Damage block works by removing a portion of the damage done, either in a set amount, such as the item Stout Shield (blocking 30 damage in a 40% chance) or in a set proportion, such as the Spectre’s Dispersion removing percentages of damage received.

Some abilities or items can further increase damage notwithstanding the armor value or type, like the Witch Doctor’s Maledict, or Orchid Malevolence’s Soulburn. In the same way, some abilities and items can also reduce damage, such as the Netherdrake’s Corrosive Skin and Hood of Defiance’s 30% spell resistance.
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Conclusion

We can see that many factors can determine how damage can be reduced or amplified. Each factor works uniquely in its own way to optimize damage in relation to the four main factors. Therefore by applying this knowledge correctly we can utilize each hero’s potential to its best.

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Last edited by caspian on Wed May 28, 2008 6:45 am; edited 1 time in total