Damage reduction is an aspect in Diablo III that most people know exists, but only a few know exactly how it operates. For most of D3, you do not necessarily need to study all aspects of the game since it is far easier and less stressful to just copy what the top ranking players are doing.

Most people start out never truly understanding why everyone puts Diamonds in their gear. Sure, it makes you tankier, but why don’t people go for other stats? Why not Armor or Health? A lot of people don’t seek out answers to these questions because “If it works for the top players, it works for me.”

In this guide, I am going to explain exactly what damage reduction is and how to best utilize it in Diablo III. While it is possible to go in-depth, I figured it was best to cover this in a way that would most benefit the people who need the info the most - specifically players who are new to Diablo or who are just not that experienced. Here, I will be explaining: What damage reduction is, what elements affect damage reduction, armor and all-resist, how to min-max, and how to utilize all that info.

Here is a quick TLDR video if you don't want to read everything below: 

                 

What is Damage Reduction?

Damage reduction is simply the % mitigation you gain when taking damage in Diablo. For example, if you have a damage reduction of 90% and a projectile that is supposed to do 100 damage hits you, your 90% reduction will reduce it to 10 damage taken. Aside from overall damage, damage

reduction is the most crucial stat that you can acquire when looking to push Greater Rifts.

What affects damage reduction?

There are many attributes to reducing damage. Below are some of the main contributors...

- Class
- Armor + All-Resist
- Dodge
- % Damage Reduction
- Reflect/Life Regen

First, the class you play has a huge effect on how much or how little damage you take. Naturally, Monks, Barbarians, and Crusaders take 30% less damage compared to the Wizard, Demon Hunter, Witch Doctor, and Necromancer. This is due to the game balancing melee classes to be able to take more damage than ranged ones; since they fight up close and personal, melee classes are more prone to taking damage.

In addition to this, main stats such as Strength and Dexterity give armor as a side bonus for increasing your damage; Intelligence gives you all-resist. This means that Strength and Dexterity classes naturally take less physical damage and Intelligence classes naturally take less elemental damage (cold, fire, arcane, lightning, poison, etc).

Next, we’ll take a look at dodge and pure % damage reduction. Dodge (more commonly known as Dodge Chance in-game) gives you a certain percentage chance to completely ignore damage taken. For example, let’s say you have 35% Dodge Chance. This means you have a 35% chance to ignore damage taken or have a 65% chance to get hit. Although this stat alone is heavily RNG-based (Random Number Generator), it still counts towards your toughness and damage reduction. Unfortunately, Dodge Chance can never reach 100% as the stat itself is multiplicative, not additive.

With pure % damage reduction, this stat flat out decreases the amount of damage you take. Of course, as with most stats in the game, this effect will stack multiplicatively and not additively (having additive % damage reduction would make it far too easy to make an invincible God toon; while the concept is exciting, it would probably get really boring really fast).  

Let’s use Aquila Cuirass and Elusive Ring to explore this a bit. Aquila gives 50% damage reduction when above 90% resource and Elusive Ring gives 60% damage reduction after casting Shadow Power, Smoke Screen, or Vault.

At first glance, you might think “50+60 would be 110. So wouldn’t I have 110% damage reduction?” Unfortunately, no. The damage reduction formula is as follows.

DR = 1 - (1-x)*(1-y)*(1-z)

DR represents damage reduction. 1 represents you. The variables x,y,z represent % damage reduction you gain from items or abilities.

Since we are using the example of Aquila and Elusive Ring, we only have 2 values of damage reduction. Hence, we will only be using the values ‘x’ (Aquila) and ‘y’ (Elusive Ring). You can add more letter variables based on how many % damage reduction factors/items you have.

Putting our numbers in the formula: DR = 1 - (1-0.5)*(1-0.6).

The result is 0.8 which equals to 80% damage reduction.

Armor and All-Resist also strongly influence damage reduction, but I will cover those in-depth in the next section.

There are other minor factors that affect damage reduction such as reflect and life regen, but the effect they have is negligible compared to everything else.

How do I best min-max damage reduction?

It may seem simple and effective to just have lots of items with % damage reduction - and it is undoubtedly effective. However, if you really want to get the most out of damage reduction, there is something else you’ll need to focus on: your ratio of armor and all-resist.

As I mentioned earlier, armor reduces damage taken from physical damage and all-resist reduces damage taken from elemental damage. In D3, a majority of the damage you take is physical. However, this does not mean you will benefit more from stacking armor alone. In fact, it is not beneficial for you to go all in on either stat.

Here is why.

These equations are defined by Blizzard.

Damage reduction from armor is = (your armor) / (50*enemyLevel + your armor).

Damage reduction from resist is = (your resist)/(5*enemyLevel+your resist).

Since toughness (your defense) is your armor multiplied by your all-resist, you want to keep your damage reduction from armor and all-resist as close as possible.

Here is an analogy to clarify. Say that you have 10 Tennis balls and 2 buckets. Say that you also have a friend who forces you to do high-school story math problems under threat of violence. He tells you to divide the balls between the buckets so that multiplying the balls in each bucket will give you the greatest possible value. Going 9 and 1 would get you a low number and really upset your friend. To avoid your friend’s wrath and get the greatest value, you would need to put 5 Tennis balls in each bucket. This will lead to the greatest multiplied value of 25.

The same theory applies to armor and all-resist. Since both values will be multiplied, you want your damage reduction from armor to closely resemble your damage reduction from all-resist. Now, let’s look back at the equations above. The only difference between the two equations is the number in the denominator: 50 for armor and 5 for all-resist.

If we’ve got 10000 Armor, 1000 All-resist, and the monster level is 70, our armor will give 74% damage reduction and our all-resist will give us 74% damage reduction. These values combined together will give you a higher damage reduction value (94.5% damage reduction) than if you had 9500 Armor and 1500 All-resist.

Hence, you want to keep all-resist and armor to a 1:10 ratio.

Classes with Dex or Str as their main stat will have an easier time gaining armor compared to all-resist. Classes with Int as their main stat will have an easier time gaining all-resist compared to armor. In other words, your Dex/Str classes should go for all-resist items and your Int classes should aim for gear with armor.

Granted, the amount of armor and all-resist you have will not be clean-cut. Just make sure you check your defensive stats; if you have too much of one or the other, try to nudge it as close to the golden ratio (1:10) as you can.

How exactly should you use this information?

Whenever you create a character, from the getgo you can now know what defensive stat you will be looking for. Dex/Str classes will want all-resist and Int classes will want armor. Instead of unknowingly accepting multiple % damage reduction effects, you can personally calculate how much effectiveness you are getting out of your items.

Although this information does not guarantee you will be rank 1 on the leaderboards for every season, this knowledge may help you push a few GRs when you thought you had capped out. Also, it never hurts to know what exactly what item is better when comparing two very nice looking ancients.

I hope this guide has helped clear up exactly how damage reduction works in Diablo III and how you can min-max it by keeping the armor-all-resist ratio. As always, happy hunting!