Damage Reduction

Damage Reduction (DR) is a measure of how much of an attack's damage a character can soak up before losing hit points. The DR value is subtracted from each incoming hit, to a minimum of zero. If you have a DR of 10 and get hit for 9 points of damage, you take no damage at all. If you have a DR of 10 and get hit for 15 points of damage, you only take 5 points of damage. DR applies only to physical weapon damage, although there is a similar concept of Energy resistance that can apply to other damage sources.

Player characters (but not monsters, apparently) can gain "Active DR" when they are holding down shift to block. Active DR is a hidden quantity, but Passive DR is easily visible on the character sheet. Multiple DR entries will be listed, and only the highest one which is not bypassed by a particular attack's properties (like Adamantine) applies.

Active DR stacks with passive DR when actively blocking.

Active DR Formula
Base active DR (with shield) = Base active DR (without shield) presumed to be =

Active DR bonuses
The following Shield Mastery feats and enhancements are added onto the above base active DR value. They all stack.
 * Shield mastery +3
 * Improved shield mastery +3
 * Dwarven shield mastery +1, 2 or 3 (for levels I, II, and III of the enhancement)

Also, the Two-weapon blocking feat increases active DR when wielding two weapons.

Example - A level 6 fighter with the regular and improved shield mastery feats, actively blocking with a +4 tower shield would have the following: Active DR = (6/2) +2 + (4+4) + 3 + 3 = 19 While this formula is correct bear in mind that improved shield mastery has a prereq of BAB 8

Passive DR bonuses
Passive DR can be provided from many sources, including: Barbarians get DR at level 2, 5, 8, 11, 14 and a +1 enhancement at levels 4 and 7.
 * the Warforged Adamantine Body Feats, or Warforged DR enhancements
 * Barbarian DR stacks with the DR of blocking.
 * Adamantine Armor (1 from shields or light armor, 2 from medium armor, and 3 from heavy armor)
 * The Stoneskin spell (DR 10/Adamantine)
 * magical items of Invulnerability (DR 5/Magic), or of Axeblock, Hammerblock, and Spearblock
 * certain other magic items, like the Bloodrage Symbiont

These passive DR sources do not stack: only the highest DR not overcome by the attack type is taken into account.

Barbarian innate DR does stack with blocking DR, this is not the case for Warforged adamantine DR

DR Aspects
While Active DR applies universally to all weapon attacks, Passive DR may be bypassed by the properties of a particular attack. Some forms of DR are vulnerable to materials (like Adamantine or Silver), alignements (like Chaos or Good), or just "magic". In this case, the property which bypasses that DR is listed after the number on the character sheet, in the form of "DR 6/Adamantine" or "DR 5/Evil". If there is no property which can bypass the DR, a "-" is listed instead.

Monster DR
Currently, DDO is known to include monsters requiring adamantine (Iron Golems), bludgeon (Skeletons and Clay Golems), and slashing (Zombies) weapons to penetrate their damage reduction. DDO also includes special weapons made from materials such as adamantine, mithril, darkwood, cold iron, silver, and byeshek.

Some monsters are vulnerable to magic weapons only. Any weapon with at least a +1 magical enhancement bonus on attack and damage rolls overcomes the damage reduction of these monsters.

Some examples include:
 * Clay Golems require Bludgeoning and Adamantine weapons
 * Flesh Renders require Good Aligned and Cold Iron weapons
 * Rakshasa require Good Aligned and Piercing weapons
 * Ghostly Skeletons require Good Aligned weapons
 * Iron Golems require Adamantine weapons
 * Skeletons require Bludgeoning weapons
 * Vampires require Silver weapons
 * Zombies require Slashing weapons