Armor As Damage Reduction

( ⇪ Adventuring Variants )

In a nutshell: You can choose to buy armor that gives Damage Reduction (DR).

When you buy armor, you can choose between “deflective” (standard-issue) and “ablative” variants of that armor. Ablative armor reduces the amount of damage dealt by an attack instead of merely turning would-be hits into misses. Ablative armor still prevents some hits outright, but also reduces the deadliness of attacks that do connect. In essence, ablative armor “gives up” some of armor’s ability to turn hits into misses in exchange for a small reduction in damage dealt by any given attack. (All other armor statistics, such as maximum Dexterity bonus, armor check penalty, and arcane spell failure chance, are unchanged.)

“New DR” = Half of “Old Armor Bonus” rounded down (untyped DR)
“New Armor Bonus” = Half of “Old Armor Bonus” rounded up + Enhancement Bonuses (if any)

Magic, Psionic, and Immaterial Armor Damage Reduction

An armor’s enhancement bonus (if any) increases its armor bonus to AC, but has no effect on the armor’s damage reduction. Mage Armor, Inertial Armor, and similar effects which grant an armor bonus can also be affected by the Armor as Damage Reduction rules, but only if you choose to make them ablative when you instantiate the armor.

Stacking Damage Reduction

The damage reduction granted by ablative armor stacks with other damage reduction of the same type (that is, damage reduction that has a dash after the number) and damage reduction provided by the armor through other means (such as impact armor or invulnerability armor).


Shields function normally in this variant, granting their full shield bonus to AC. Unlike with armor, a shield’s effectiveness is measured wholly by its ability to keep an attack from connecting with your body.

Table: Natural Armor and DR
Natural Armor Bonus Damage Reduction Subtract from Natural Armor
0-4 none 0
5-9 1/- 1
10-14 2/- 2
15-19 3/- 3
20-24 4/- 4
25-29 5/- 5
30-34 6/- 6
35-39 7/- 7
40-44 8/- 8

A creature’s natural armor can also be ablative. Divide the monster’s natural armor bonus (not including any enhancement bonus) by 5 to determine the monster’s damage reduction. The same value is subtracted from the monster’s natural armor bonus to find the monster’s new AC. These calculations are summarized in the table.

If the creature already has damage reduction, either add the value gained from natural armor (if the existing damage reduction is of the same type) or treat it as a separate DR value (if it is of a different type).

Armor As Damage Reduction

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