[Article]Guide to Damage Block

[Phoenix]

Guide to Damage Block

There were a lot of people having doubts concerning damage block (Vanguard/PMS/StoutShield/KrakenShell) so I decided to make a guide for this.

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Table of Contents

1. What is Damage Block?
2. Ways of Damage Block
   • Stout Shield
   • Poor Man's Shield
   • Vanguard
   • Kraken Shell (Tidehunter)
3. Mechanics of Damage Block
   • What type of damage is reduced?
   • Interaction of Damage block with Armor
   • Stacking Damage Block
   • Actual chance of Damage Block
4. FAQs
   • Krobelus' spirits vs Damage Block
   • Illusion damage vs Damage Block
   • Mana Shield with Damage Block
5. Credits

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I. What is Damage Block?

The reduction of the damage you receive when you get hit by anything with damage type physical. This means it will reduce damage from normal attacks and from spells with damage type 'physical' or 'mixed'. All Damage Blocks are based on Hardened Skin Skill.

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II. Ways of Damage Block

Currently, physical damage can be blocked by 4 ways in DotA:-

1. Stout Shield
Gives a 60% chance to block 20 damage if the wielder is melee, or a 60% chance to block 10 damage if the wielder is ranged.

2. Poor Man's Shield
Gives a 100% chance to block 20 hero damage and a 60% chance to block 20 non-hero damage if wielder is melee.
Gives a 100% chance to block 10 hero damage and a 60% chance to block 10 non-hero damage if wielder is ranged.

3. Vanguard
Gives a 70% chance to block 40 attack damage if wielder is melee, or 70% chance to block 20 damage if wielder is ranged.

4. Tidehunter's Kraken Shell
Gives 100% chance to reduce 7/14/21/28 damage.

Only the details of damage block are written above. Other effects of the items/skill will not be discussed here.

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III. Damage Block Mechanics

1. Damage Block reduces physical damage type. This may be due to normal attack or by spells with physical damage (like Slardar's Slithereen Crush) or by spells with mixed damage type (like Beastmaster's Wild Axes).
Refer to this for more information on spell damage type.

2. Damage Block occurs before any armor reductions.

Example

Let us suppose your hero (melee) has 5 net armor (23% damage reduction approx). You've made a Vanguard and you get hit by 100 damage, then your hero will have:

1. a 70% chance to take 46 final damage. [Damage Block from Vanguard triggers. Damage Received = (100 - 40) x 0.77]

2. a 30% chance to take 77 final damage. [Vanguard did not proc. Damage Received = 100 x 0.77]

Refer to this for more information on Order of Damage Calculations.

3. Stacking Damage Block - When our hero has more than one damage block source...

Only one Damage Block can proc/trigger at a time. The last acquired damage block is checked first of all, if it doesn't proc only then the next one is checked.

Items counts as acquired when they are picked up and abilities counts as acquired when you learn the first level of the ability (any subsequent leveling will not make the ability count as re-acquired).

The chance that any of the sources you have which provides damage block will trigger follows a diminishing stacking pattern as can be seen by the generic damage block formula.
The following formula is used to calculate the chance that any source you have will trigger:

Chance to block = 1 - [(1-X)*(1-Y) ...]

{X, Y, ... } are replaced with the percentual chance that the source will trigger described as a decimal value.

Examples

1. If you buy a Vanguard first and then level Kraken Shell, the damage block from Vanguard will never trigger coz Kraken Shell (with 100% chance to proc) was the last acquired Hardened Skin Skill. But you can drop and repick the Vanguard so it becomes the last acquired damage block item and would be checked first for damage block.

---x---x---

2. Let us suppose you complete a Vanguard and then buy (an additional) stout shield. The last acquired Hardened Skin here is Stout Shield so it will be checked first for damage block. Your hero will have:
-> a 60% chance to block 20/10 damage if the wielder is melee/ranged.
-> a 28% (70% of remaining 40%) chance to block 40/20 attack damage if the weilder is melee/ranged.

[So, basically you're at a loss here. Drop the Vanguard and pick it up again to make it the last acquired item.]

---x---x---

3. How will 2 Vanguards stack with each other?

If a melee hero has 2 vanguards, your chance to block 40 damage is 91% = 70% (last acquired Vanguard procs) + 21% (70% of remaining 30% if the last acquired Vanguard does not proc but the other one does)

Note that 80 damage will not be blocked in any case (a common misconception).

4. Actual chance of Damage Block

The chance to trigger Hardened Skin is based on Pseudo Random Distribution. This makes the actual chance to block a bit lower than the stated value.

Skill/Item	Stated Chance	Actual Chance
Stout Shield	60%	53%
Poor Man's Shield	100%(hero damage)	100%(on/off not based on PRD)
Poor Man's Shield	60%(non-hero damage)	53%
Vanguard	70%	60%
Kraken Shell	100%	100%

For more information on Pseudo Random Distribution read this.

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IV. FAQs

1. Krobelus' spirits/ghosts vs damage block.

Q. Will a Vanguard help me reduce damage from Krob's ulti?

No

Krobelus' spirits have the ability [Locust] and damage block does not reduce damage from units having Locust ability.
Besides Krobelus spirits, dummy unit summoned by Corrosive Skin (Viper) has the locust ability that always deals 1 damage.

2. Images vs Damage block

Q. Assuming a Phantom Lancer has 100 base damage then his images would do 25 damage when they hit a target. But if it gets blocked by a melee vanguard would the damage be (100-40) * .25 = 15 damage or (100 * .25) -40 =0 damage?

0 damage

The illusion damage reduction is applied before damage block. Strategically talking, this makes Vanguard and other ways of illusion damage quite effective against illusion's physical damage.

3. Mana Shield (Medusa) with Damage Block

Q. Will the damage reduction happen before mana shield absorbs the damage ? or will mana shield absorb the damage and then damage reduction works?

This has two possibilities:

1. If you acquire damage block first and then activate mana shield - In this case both work together with the mana shield reducing the incoming damage first of all.

2. If you acquire damage block after activating mana shield -In this case mana shield activates only if damage block does not trigger.

Pro-tip: Always deactivate and then reactivate mana shield after making a damage block item.

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V. Credits

- Robzor e00E
- Somewhat inspired from Damage Blocking Guide by gradenko_2000 @ dota-allstars.com
- All mech fags of Advanced Mechanics forum.

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Do report any errors/typos in the guide. Thanks for reading.

Antiweltteilchen rocks! and I totally didn't copy this idea from his guide

[Phoenix]

Changelog

1 Nov, 09
- Posted the Guide. lolz

2 Nov, 09
- Added trigger chance of Damage Block
- Added formula for stacking Damage Block (e00E)
- Added FAQs
Krobelus' spirits vs Damage Block
Illusion damage vs Damage Block
Mana Shield with Damage Block
- Changed color scheme (Cáno)

18 Mar, 10
- Updated guide for 6.66b

[Cáno]

spells with physical damage (like Slardar's Slithereen Crush)

Everyday I learn something new.

Now, a few things:

• Damage Block - Locust interaction
• PRD
• It messes up Mana Shield if acquired after activating Mana Shield (needs tests/confirmation)
• antiweltteilchen fails

The last acquired damage block is checked first of all, if it doesn't proc only then the next one is checked.

I always have problems with this. Is it right?

the damage block from Vanguard will never trigger coz Kraken Shell

That's nitpicking but as this is guide it should be kept in formal style, I think.

the damage block from Vanguard will never trigger coz Kraken Shell

Close the parenthesis.

[Robzor]

II. Ways of Damage Blocking

First of all I'd like to comment on this; Please call it Damage Block at all times as to not confuse the reader, this headline may suggest that it may involve other forms of damage reductions as well.

Please skip the teal, try using some bold and italic text instead or use use other shades of green.

Tbh, use this damage guide instead since I've updated it to be correct for the latest version not to mention the tavern structure change.

Formula introduction with the obligatory explanation, currently you have sample cases but do not introduce the relevant formula used for these calculations. This is the most important part when it comes to my feedback.

Tell readers that the base spell is Hardened Skin (No, not Resistant Skin :P).

I could send you a draft version I had on a damage block article I was compiling if that'd be interesting material to work with, unless you feel that making some alterations would suffice (who knows, you might want to read it anyway).

Originally Posted by Cáno

I always have problems with this. Is it right?

They are checked in reverse order of acquisition indeed.

[Phoenix]

Originally Posted by Cáno

antiweltteilchen fails

Rule#1 Anti may fail 0.000000001% chance but he's Awesome! If you don't agree, agree to Rule#2. Else, stop and agree.
Rule#2 Anti's a success 99.99999999% chance and so he's Awesome! If you don't agree, read Rule#1. Else, stop and agree.

Greets
Ph'oenix
___________________

Originally Posted by Robzor

Formula introduction with the obligatory explanation, currently you have sample cases but do not introduce the relevant formula used for these calculations. This is the most important part when it comes to my feedback.

That I wanted to include and was relying on anti's help but he's offline. Can you help me with that?

Originally Posted by Robzor

I could send you a draft version I had on a damage block article I was compiling if that'd be interesting material to work with, unless you feel that making some alterations would suffice (who knows, you might want to read it anyway).

I'd love to as long as it doesn't involve too much code study. Plz send me whatever awesome content you've written.

Will update the guide a little and then watch 3rd MYM game (man... they're busy nowadays) consecutively the same day and then go to sleep.

[Audacious]

I am not sure what the:

"1. If you buy a Vanguard first and then level Kraken Shell, the damage block from Vanguard will never trigger coz Kraken Shell (with 100% chance to proc) was the last acquired Resistant Skin Skill. Again, if you drop and repick the Vanguard then it would be checked first for damage block and then Kraken Shell will come into picture."

Means.

Whats with the: "Again, if you drop and repick the Vanguard then it would be checked first for damage block and then Kraken Shell will come into picture."?

[Robzor]

Check your premenstrual syndromes.

[Phoenix]

Originally Posted by Audacious

Whats with the: "Again, if you drop and repick the Vanguard then it would be checked first for damage block and then Kraken Shell will come into picture."?

Sorry for bad English.

Also, somebody tell me how to change caption of spoilers.

[Cáno]

Originally Posted by e00E

Check your premenstrual syndromes.

(._. )

The green tone of Headings doesn't fit now.

[SoletLuna]

Originally Posted by Phoenix

Rule#1 Anti may fail 0.000000001% chance but he's Awesome! If you don't agree, agree to Rule#2. Else, stop and agree.
Rule#2 Anti's a success 99.99999999% chance and so he's Awesome! If you don't agree, read Rule#1. Else, stop and agree.

Greets
Ph'oenix

Disagree hard o.o

Anyway, what Robzlol said and such o.o

[Elune]

What about the interaction about "Damage Block and Enrage Ursa with Furry Swipes"？
How to Calculate it？

[starfighter9]

Fury Swipes is bonus damage added on to your main attack, so damage block will treat it and your main attack as one instance (i.e. no separate block for fury swipes alone, so if you do 100 + 25 damage and vanguard procs only 40 damage blocked from 125). Enrage is added to your normal attack so there also isn't any damage block for it. However, the extra fury swipes from enrage is anotehr damage instance by itself and hence is subject to another instance of damage block.

[Moonshine]

Hi OP, thanks for a great guide. However, would u please tell me about how this will stack with Centaur's ultimate?

[starfighter9]

^ I don't see how +str and damage block will possibly interact in any undesirable way.

[Moonshine]

Hi starfighter9, +str is not the only thing Centaur's ultimate does.

[starfighter9]

What? All it does is add 12/24/36 str.

[Moonshine]

Hi starfighter9, you're right, I misread the in game description said that it absorbs damage. Thank u for pointing it out.

[Phoenix]

Originally Posted by Cáno

The green tone of Headings doesn't fit now.

Is it better now?
Will add stuff on PRD and Locust Interaction soon. Am a little confused on problem with Mana Shield but will figure it out and add later.

Greets
Ph'oenix
___________________

Originally Posted by Moonshine

Hi OP, thanks for a great guide.

Thanks. ^^

Originally Posted by Moonshine

However, would u please tell me about how this will stack with Centaur's ultimate?

For a moment I was like

[Trysaeder]

Graphs by Malle

Iron buckler: Stout
Helm of the black legion: Vanguard
Ringmail: Chain mail
Platemail: Platemail

(Come to the dark side, we have Malle)

[Cáno]

Originally Posted by Trysaeder

Come to the dark side, we have Malle

Do we?

Edit: Try this color: #00aa00.

Greets
Cáno