Damage reduction: how does it work?

I know on the surface this seems self explanatory but I’m curious if anyone knows how this works exactly? There are skills and items that provide various “damage reduction” but I’m not sure how/when this reduction is applied. Does it get applied to everything? Shields and health pools or only health? Like if I have 20% damage reduction does that mean my shields take 20% less damage or my health once my shields are gone or both?

When damage reduction is applied varies per item or skill, so unless you list specifics I can’t really help there. Generally unless a condition is stated it applies at all times, for both health and shields.

As for the maths of how damage reduction works say you get hit by a bullet then:

Damage taken = (bullet damage) x 1 / (1 + damage reduction)

So for your example of 20% damage reduction and lets say a bullet that usually deals 100 damage.

Damage taken = 100 x 1 / (1+0.2) = 83.333

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Strange isn’t it because 100 - 20% = 80

83.333 would only be a reduction of -16.667%

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+20% damage reduction isn’t equal to 20% reduced damage taken but +20% effective life pool or 20% more damage required to take you down.

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Reduction and Resistance are not interchangable terms. Some Eridian artifacts in BL2 incorrectly indicate “resistance” when they truly are reductions.

1 - DamageReduction = 1/(1+DamageResistance)

If DamageReduction is listed as 30%, what is the DamageResistance?

1 - DamageReduction = 1/(1+n)
1 - 0.3 = 1/(1+n)
0.7 = 1/(1+n)
1+n = 1/0.7
1+n = 1.43
n = 0.43 or 43%

So a DamageResistance of 43% is equivalent to a DamageReduction of 30%. Crazy, but true.

WTF is damage resistance? I don’t recall ever seeing that anywhere or do you just mean like elemental resistance?

Damage resistance includes elemental DoT resistance. It also includes non-elemental bullet damage for a few so-called resistance relics. “Non-elemental resist 28%” or similar. What it actually does is multiply the incoming damage by 0.72, which would be a true reduction.

Gearbox should have been consistent with terms to avoid confusion.

Anyways, anything in this n position in the denominator is defined as a resistance: 1/(1+n)

The important concept is that “100% resistance” doesn’t grant immunity. It merely cuts damage in half. So we can have very high resistance sums, but still suffer (or inflict) damage.

A 120% damage reduction, on the other hand, is nonsense. Any damage reduction greater than 100% can’t reduce a zero value to a negative value. However, a damage resistance of 120% is valid.

1/(1+1.2) = 1/2.2 = 0.45

So 100 damage is converted to 45 damage, in that case.

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Available on coms as both a primary effect (for Amara) and secondary stat, as well as on the RR. EDIT: And as two different anointments, one passive with terror and one tied to skill end.

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As far as my tests go, damage reduction is calculated like @Prismatic_Me detailed in his post (the same way it was in BL2 and TPS), while damage resistance can be directly translated into 1:1 damage mitigation. E.g. The Transformer and the Red Suit shield with 100% resistance do make its wearer immune to their corresponding damage type.

Every modifier in BL just states the value somewhere in the actual formula, not necessarily how you’d expect the outcome to be. If it worked like that, with a few skills and items you might be able to reduce damage taken to 0 or below, which would obviously break the game. Like with additive and multiplicative modifiers, if something says +20% damage that doesn’t necessarily mean the whole damage is multiplied by x1.2. It just means that +20% is put somewhere in the formula.

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The terms are flipped. Resistance can be any value since it is in the denominator. Reduction is a multiplier between 0 and 0.9999.

Those items should state 100% damage reduction versus specific threats.

Generally if one item offers 30% damage reduction and another item offers 30% damage resistance, the first one is superior. Gearbox item cards are not written by perfectionists. It’s a video game afterall.

Does it really work that way?

Man that’s misleading.
One would expect 20% damage reduction to actually be 20%, not 17%

That’s pretty shady

It seems funny at first, if you want another way to think of it try imagining Damage Reduction as being how much damage the enemy has to deal in order to kill you.

It makes you take less damage. However they don’t tell you that having it just provokes the enemies into hitting you harder which kinda negates the benefit… >.>