Item passive stacking

Item passive stacking describes the interactions between multiple items that have similar effects. The stacking of effects and items falls into different categories, and each category behaves differently.

Independent stacking
Effects stack independently if they stack additively. This is the simplest and most intuitive type of stacking: multiple effects or attributes will add to each other.


 * Example:


 * at level 25 with a has:
 * Armor = base armor + bonus armor = +  =  armor

Effects that stack independently

 * Bonus attack damage
 * Bonus attributes (strength/agility/intelligence)
 * Bonus mana/health (static amount)
 * Bonus health regeneration/mana regeneration
 * Bonus attack speed
 * Bonus armor
 * Lifesteal
 * Mana Break (with the exception for Anti-Mage's mana break which does not stack with that of Diffusal Blade)
 * Movement Speed bonuses from different categories (some items fall in the same category and therefore only the highest value applies, for example: Boots)
 * Cleave damage (with the particularity that the damage from multiple instances of cleave is not actually added: each instance deals independent damage)
 * Maim

Multiplicative stacking
Values that are stacked in a multiplicative manner have diminishing returns. The stacking effect can be calculated with the formula:

where each instance is a percentage.

Example:
 * with level 4 and a  has a magic resistance of:
 * 1 - (1 - ) × (1 - ) × (1 - ) = %

Effects that stack multiplicatively

 * Magic Resistance
 * Evasion
 * Status Resistance

Limited stacking
These effects stack multiplicatively, but when two instances of the same effect happen at the same time, only the highest value is kept or the duration is refreshed.

Critical Strike
Critical strike procs are rolled from the strongest to weakest multiplier, and stop rolling once proc occurs, so that two critical strikes cannot proc on the same attack, resulting in a diminishing behavior.

For example holding a  (230%) cannot crit when using  (350%).

Damage block
Only one instance of damage block can proc at a time. The highest damage block value has priority.

Bash
The strength and damage components of multiple s and s will independently stack, but the bash chance will not.

Chain Lightning
The attack speed and damage components of multiple s and s will independently stack, but the chain lightning chance will not.

Auras
Auras provided by items do not stack with themselves, since they place a buff/debuff on the unit. Only the aura with the highest value will work.

Сочетание пассивных способностей предметов 物品被动效果叠加