Simple defense mechanics explanation

[VHD]

I've been hunting forums and websites for quite a while now, trying to get a clear picture of how defensive attributes (armor, blocking, resists, etc) work in Diablo 3. I've gone through lots of tables, equations, and calculations but I still don't have any good intuition. I've compiled some basic questions/answers to help. Big thanks to everyone who has contributed in this thread!

1) How does armor reduce damage?

Armor reduces all incoming damage by a percentage - including elemental damage. This % damage reduction takes place before shield blocking and is based on your total armor and the enemy's level.

2) How do resistances and "resist all" work?

Resists work as additional 'armor' to further reduce specific types of damage. These types include Fire, Arcane, Cold, Lightning, Poison, and Physical. Each point in a resistance is equivalent to 10 points in armor, but only works on that particular type of damage. "Resist all" (as the name implies) adds to each of these 6 resistances, providing a very compact collection of defensive boost.

3) How does shield blocking and dodging work?

Dodge is a chance to avoid an attack entirely. It works on individual attacks as well as channeled/ground effects. Shield blocking provides a chance to block a fixed amount of damage after it has been reduced by any armor/resistances. Blocking works on individual attacks as well as channeled/ground effects. Shield blocking works while moving (unlike Diablo 2).

4) In what order is damage mitigation applied (first to last)?

Dodge
Armor, Reduction Skills (Iron Skin, Blur, etc), Resistance, Barb/Monk 30% reduction
Shield Block
Absorption Skills (Diamond Skin, etc)

5) What kinds of elemental damage do champion/boss modifiers do?

Arcane Enchanted = arcane damage
Frozen = cold damage
Molten = fire damage
Plagued = poison damage
Electrified = lightning damage

After further investigation, I believe the following:
Mortar = fire damage (?)
Desecrator = physical damage (?)
Fire Chains = fire damage (?)

I'll be editing this post to add more questions and answers. Feel free to contribute either!

Thank you to: Raesene, Ohlmann, and zakaluka for providing insight. For those who wish to dig into the details, HamletEJ has written a useful blog post on detailed armor mechanics:

http://iam.yellingontheinternet.com/...in-diablo-iii/

(original post):

I've been hunting forums and websites for quite a while now, trying to get a clear picture of how defensive attributes (armor, blocking, resists, etc) work in Diablo 3. I've gone through lots of tables, equations, and calculations but I still don't have any good intuition.

Can anyone help answering a few basic questions or point me towards an excellent guide?

1) Does armor reduce ALL incoming damage? (physical hits and magic attacks)

2) Does Resist Fire (for example) only reduce damage from magic fire attacks?

3) How is Physical Resist different from armor?

4) Does a successful shield block (and accompanying damage reduction) occur before or after armor/resist damage reduction?

5) Does dodge apply equally to any (physical or magic) attack? What about steady dot based damage (like poison) - can that be blocked?

I'll be editing this post to add answers and more questions. If someone else has already started a similar thread, I'd be happy to merge.

[Raesene]

1) Yes

2) Yes, but there is no distinction for "magic" fire, it's either fire or "not fire".

3) Physical resist only mitigates physical damage. Armor mitigates all elements (consider physical to be an "element").

4) After

5) Yes and no, there are some attacks (mostly ground stuff) that I believe can't be dodged at all. I am unsure about dots. If you stand in a continuous stream of fire like those giant blow torches in late Act 3, you'll see a lot of dodges and blocks pop up.

[VHD]

Thank you so much, Raesene. Given that information, why do people care so much about building a high resist all in late Hell and Inferno when cold and lightning dmg (for example) are so rare?

Seems like stacking up armor and possibly fire (and maybe poison?) resist would be far more important...

Also, does physical resist have the same scale as elemental resists? (As I understand it, 10 points of armor mitigates same amount as 1 point of resist)

Another question - is it true that Morter, Desecrator, and Molten are all forms of Fire damage? Or are some of those modifiers physical/arcane?

[Raesene]

Thank you so much, Raesene. Given that information, why do people care so much about building a high resist all in late Hell and Inferno when cold and lightning dmg (for example) are so rare?

Seems like stacking up armor and possibly fire (and maybe poison?) resist would be far more important...

Because of item budget pretty much. Let's say, for example, that the only resists you really care about our fire/poison/physical. One affix will cover all of those resists, where you'd need to have three affixes "spent" to cover all three of them. Ideally, you'd find an item that has both +ALL and the specific resist(s) you want.

Also, does physical resist have the same scale as elemental resists? (As I understand it, 10 points of armor mitigates same amount as 1 point of resist)

Yes, physical is really no different than any other element. It just happens to be a fairly common one.

Another question - is it true that Morter, Desecrator, and Molten are all forms of Fire damage? Or are some of those modifiers physical/arcane?

I don't know for sure. I'm 99% positive that molten = "fire", but I'm less sure about the other two.

[Ohlmann]

5) Yes and no, there are some attacks (mostly ground stuff) that I believe can't be dodged at all. I am unsure about dots. If you stand in a continuous stream of fire like those giant blow torches in late Act 3, you'll see a lot of dodges and blocks pop up.

I have not seen any ground effect that I couldn't dodge as far as I could tell. About the resistance, it's not the total amount of thing that damage you via an element that is important. Without lightning resistance, for example, electrified are a nightmare. And with 4 affixe per elite in inferno, you can't hope not to encounter electrified often. For a cac character, every damage type have an affixe that became impossible to kill if you don't have an at least passable resistance for it. Ranged character may feel differently, but as Raesene said, when you need electricity, physical, and fire resistance, you can just use all resist gear. (BTW isn't desecrator arcane ?)

[zakaluka]

you can also block ground effects, another question the OP asked.

[VHD]

A few more questions:

1) Can anyone provide confirmation on this (I found it on the DiabloWiki, but parts of it may be outdated):
Mortar = fire damage
Desecrator = physical damage

2) Can anyone provide information on what type of damage Fire Chains deal? (I'd assume fire damage?)

3) Do skill/rune damage reduction and absorption modifiers (for example, Iron Skin or Diamond Skin) apply after all other damage mitigation (from armor, resist, block) has taken place?

4) Any confirmation/rejection of this statement from the DiabloWiki? "Presumably blocking will not work while running in Diablo III, though this is not confirmed."

[RazeBarb]

I always thought Desecrator is fire damage.

[Raesene]

A few more questions:

1) Can anyone provide confirmation on this (I found it on the DiabloWiki, but parts of it may be outdated):
Mortar = fire damage
Desecrator = physical damage

2) Can anyone provide information on what type of damage Fire Chains deal? (I'd assume fire damage?)

3) Do skill/rune damage reduction and absorption modifiers (for example, Iron Skin or Diamond Skin) apply after all other damage mitigation (from armor, resist, block) has taken place?

4) Any confirmation/rejection of this statement from the DiabloWiki? "Presumably blocking will not work while running in Diablo III, though this is not confirmed."

3) Yes, I believe so.

4) I don't think that statement is true at all. I'm not even sure why the DiabloWiki made it.

[The Rockman]

A few more questions:

1) Can anyone provide confirmation on this (I found it on the DiabloWiki, but parts of it may be outdated):
Mortar = fire damage
Desecrator = physical damage

2) Can anyone provide information on what type of damage Fire Chains deal? (I'd assume fire damage?)

3) Do skill/rune damage reduction and absorption modifiers (for example, Iron Skin or Diamond Skin) apply after all other damage mitigation (from armor, resist, block) has taken place?

4) Any confirmation/rejection of this statement from the DiabloWiki? "Presumably blocking will not work while running in Diablo III, though this is not confirmed."

1. Dunno haven't tested, but I assume Mortar does fire base on graphics.

2. They will do fire dunno if they do any other damage types as well.

3: All % reduction mods thats iron skin Blur etc all go in to the damage table before Block.
Diamond Skin is an absorption skill and goes last after all over defense checks (basically its extra HP for the duration).

4. Only thing that effects block is % block rating (when ever you take damage game does a block check).
I think its a bit of left over text from ages ago when people thought block might work like D2.