Absorption is a special modifier that completely erases a certain amount of damage.
In Diablo II, damage absorption usually works on a damage of a specific type, as well as heals the user that amount of damage before they take damage from the rest of the hit.
There are two types of absorption modifiers: one that reduces damage by a specific number of hit points (e.g., "+15 Fire Absorb" on Hellmouth), and one that reduces damage by a specific percentage (e.g., "Cold Absorb 20%", as found on Raven Frost).
The value of absorption modifiers varies greatly due to how damage is inflicted:
Absorbing lightning damage is the most useful since lightning tends to hit in multiple small bolts. Ten points of lightning absorb can completely neutralize a Lightning Enchanted boss, if it's emitting dozens of 6-8 damage charges. In contrast, ten points of fire absorb, even after healing, would make hardly any difference against a 500 damage Meteor.
Absorb Magic Damage modifiers work against all types of non-physical damage.
Absorb X% Damage modifiers are most useful against fierce elemental damage monsters.
Absorption is calculated as follows:
- For elemental damage, calculate resistance first.
- Remove percentage absorption, if any.
- Remove hit point absorption, if any.
- Add healing, up to maximum hit points.
Example: A player with Raven Frost and 75% Cold Resistance takes 400 hit points of cold damage. The 75% resistance takes the damage down to 100 HP. The Cold Absorb takes 20% of that figure off, leaving 80 HP, and then those 20 HP are converted to healing, leaving a final damage of just 60 HP.
As a result of the formula, the effective damage reduction from Absorb is twice the listed amount: Raven Frost, for example, reduces cold damage by 40 percent.
The maximum effective percentage absorb that has any effect is 40%.
Absorption returns in Diablo III, but works in a slightly different way, absorbing damage like Mana Shield in Diablo I, except that it consumes the shield's own capacity rather than Mana. Some skills protect the character (or their ally) with a shield of force, barrier of pure diamond or a shroud of holy energy, making enemy damaging attacks drain from the shield instead of the victim's Life pool. Shield fully benefits from all types of protection, so the exact same amount that would otherwise go to unsaved damage depletes the shield potency. If the shield cannot ward off all damage, it disappears, making the remaining amount be drained from the character's Life as normal.
Note that absorption, unlike complete immunity, does not protect from secondary effects of an attack; that is, all effects other than damage will apply as normal. Moreover, for all effects that trigger on a damaging hit, even a fully absorbed attack still counts as taking or inflicting unsaved damage. Even Life Steal and other similar effects (what few remain in game) work on absorbed damage.
Due to the amounts of damage skills and effects can absorb being limited, absorption builds benefit greatly from increased armor and resistances. Some skills calculate the amount of damage absorbed based on the character's maximum Life, while other use fixed amount (but tend to increase its effectiveness from innate healing attributes).
A number of skills exist (such as Ignore Pain) that also decrease the unsaved damage by percentage, regardless of how high it is. These skills take effect before absorption, so combining both may greatly reduce the total amount of damage taken.